By Barrie Walker 29/7/1997


This is all derived from the postings to this group, or possibly discussions with friends, who would have been posting had they access. I myself have no extraneous knowledge of the subject. 


Wasps seem to come to life in the spring and die off in late autumn. Unlike bees, they build new bykes each year. They never use an old byke and the presence of an old one doesn't, of itself, encourage them to use that place again, but what encouraged them to build there in the first place (e.g. proximity of fruit trees) may well still be present. You may have to address this for a complete solution. 

The size of the bykes can vary wildly from that of a golf-ball to that of a football. The larger ones can house tens of thousands of wasps. During the winter, the byke will be empty - the queen away hibernating somewhere warm and the workers all dead - so dealing with that [old] byke achieves nothing - indeed, some say that they make very good insulation.

On the other hand, sealing the hole they were getting in by will give that place one less tick in the `Which Byke?' guide. Note that, if the hole is needed for ventilation, some suitably-sized mesh could be used. 

In Defence of Wasps

You should think twice before getting rid of a byke unnecessarily as the wasps are hard working gardener's assistants, eating insects, caterpillars and other nasties. You may be well to actually encourage at least one byke about the garden (though not in the house) as they do a fine job of culling greenfly and the like. 

Dealing with Them

There follows various ways of dealing with bykes once found. In the DIY section, inclusion does not suggest suitability. 


1. Professional Exterminators

Typically they will come and remove the byke and spray powder insecticide around. This may cost up to UKP 50 +.

2. The Local Council

Phone the council pest control people and they'll send someone to deal with it. Cost varies from place to place, with some places even doing it free of charge (which sounds like a very good deal to me if it's on offer) but this is getting rarer.

3. Your local Angling Club

Contact the secretary of your local club. They use wasps as bait and will often come and remove the byke for you free of charge. 


4. Laisser Faire

If it's late enough in the season and you can stand it, just leave them be. Once the season is over (no more wasps), block the entrance hole (see above) and hope for the best - it worked for me. However, some people are allergic to wasp stings, so this may not be a valid option. For the other methods you need to be able to see the byke, and you need to be active when the wasps aren't, i.e. when it's cold and/or after dark. Some claim to have done this often without once getting stung! But be careful, protect all areas of skin especially the face. Multiple stings can be potentially life-threatening. Whatever you do, don't be a hero!

 5. Obtain (the only product mentioned by name in the postings) a powder by Bio called Wasp Nest Destroyer costing (then) UKP 2.65. Bearing in mind the precautions above, puff the powder on the entry to the bykes. One application should suffice. An ant-killer powder may be just about as effective.

 6. You should be able to get an aerosol spray or non-aerosol liquid jet (c. UKP 5) from your local garden centre. Bearing in mind the precautions above, spray the concoction on the byke itself. With the liquid jet you may not have to get any closer that 15ft depending on your ability to aim.

 7. Obtain a 200ml tin of lighter-fluid (contact poison for wasps) and a 350ml spray can of clear acrylic spray (e.g. a Holts touch-up can!). After dusk, when they're drowsy, coat anything that flies in the acrylic. Once everything's quiet, drench the byke in lighter fluid. Later, when there's no more buzzing, remove the byke and, preferably, burn it. Note that lighter fluid is basically petrol and is highly volatile and inflammable.

 8. You can also get an aerosol that emits a freezing blast and literally freezes and stops them in mid flight. You can direct the same product into the byke too. You've still got to kill them but it may give you a breathing space and allow you to do the deed during daylight.

Pedalling the `Byke' Word

Andy Dingley enlightened (some of) us: "Etymology is unknown, and although it originally applied to wild bees (not a hive or skep of cultivated bees), it also has a long pedigree of application to nests or swarms of wasps, hornets and even flies."


By Matthew Marks 1/4/1998

People often wonder if holes in items of furniture etc are a new or an old attack. If they are new, the holes will be clean (new-looking wood visible inside), and there will be little piles of woody dust below them, if the item hasn't been moved. If old, the holes will be dirty.

It is recommended to treat with dedicated woodworm fluid, rather than general purpose timber treatment. Follow instructions on the can.


By Stuart Grant 21/9/1998; edited by Matthew Marks

Sometimes plastered solid walls become "blown", i.e. the basecoat becomes separated from the wall behind. This can be detected by tapping the plaster: it will sound hollow where it is blown. It could stay like that for many years without trouble or it could crumble away and fall at the next shock wave from a heavy lorry passing. If it falls off in 3 years you'll have no comeback on today's plasterer. 

A simple fix is to glue the loose areas back to the masonry with PVA bonding. Drill a 1/4inch hole sloping 45deg down near the top of the loose area and work a six inch length of 1/4" neoprene tubing into the hole. Seal around with Blutack. Attach the other end of the tube to a washing up liquid bottle with the bottom cut off to form a funnel and securely tape it to the wall above. Fill the funnel with PVA watered down to the consistency of full milk and leave it to flow slowly into the hollow behind the loose plaster. Pressing the loose area gently in and out will help the flow and spread the bonding. A second hole at the bottom of the area will tell you when the bonding has got there. Don't try and hurry things with a squeezy bottle or you could push the plaster off and break it. It should be fixed and dry in 24 hours.

 PVA can also be used to fix sagging lath and plaster ceilings: prop the sagging plaster back into place, and apply watered-down PVA from above. 


By Rick Hughes 3/12/1999

For those who want some mainly historic details on Lime ... are we sitting comfortably, then I'll begin.

Ordinary Portland Cement invented in 1824 is what is used in almost all new buildings, but lime has it's uses especially in the renovation of old properties.

Lime mortar consists of a mixture of sand and lime.

Lime is produced by the burning of limestone (chalk) in a kiln for a period of around 4 days at between 900 and 1000 degrees C. This is known as Calcining, and the resultant substance usually in lump form, or crushed to a powder is known as 'Quicklime.' Chemically it is Calcium Oxide. There was a whole industry associated with this, and the guys involved were called Lime Burners.

Traditionally, lime was taken in this form to a site, a pit dug, the Quicklime put in it and then a quantity of water added. This results in a VERY vigorous exothermic chemical reaction which gives off a vast amount of heat and expands considerably. If the water quantity was accurate the lime expands, it disintegrates and falls into a powder. However normally excess water is added to produce a paste known as 'Lime Putty'.

The above action is chemically termed hydration and historically the process is known as 'Slaking'. It is very important that full thorough slaking occurs, otherwise any unslaked lime would on the addition of water to the mortar continue slaking in the wall ... causing expansion, cracking and weakness. If Quicklime is left exposed to the atmosphere it will eventually 'Air slake'.

Nowadays lime is usually purchased in bags of scientifically prepared 'Slaked Lime' this is made by a fast continuous process, making it cheaper. Either by controlled burning or by a pure chemical process.

It has advantages :

  • It is consistent
  • It is fully burnt and thoroughly hydrated
  • It can be stored longer without deterioration
  • 'usually' better results than lump lime

However its has a MAJOR disadvantage that it suffers from blowing ... this is the expansion of small lumps of lime causing fractures in finished work.

There are different classes of LIME

  • High calcium lime
  • Semi-Hydraulic lime
  • Hydraulic or Eminently Hydraulic Lime

High calcium lime

Is also known as 'White lime' or 'Fat lime' and is classed as quick slaking due to being almost pure calcium. It has outstanding handling characteristics and is very plastic, a joy to work with.

Semi-Hydraulic lime

Is also known as 'Grey Lime' has a lower Calcium content and higher level of impurities, and is less plastic.

Hydraulic or Eminently Hydraulic Lime

Also known as 'Lias' contains a greater proportion of impurities, making it more difficult to work. Often referred to as 'Learn' lime.

Impurities in Lime is not always a bad thing, and in fact for brickwork is often desirable as it increases strength of the finished mortar. There are many known impurities, such as magnesium, such 'Magnesium Limes' are used because they have greatly increased hardening properties compared to High Calcium limes.

Settling of Lime

Settling is the action that occurs after slaking and depends on the slaked lime absorbing CO2 from the atmosphere. This changes the soft particles of slaked lime are converted to comparatively hard crystals of Calcium Carbonate.

The sequence is thus:

Calcium Carbonate...burnt...Calcium Oxide...water added (slaked)...Calcium Hydroxide...absorption of CO2 from atmosphere...Calcium Carbonate
- more or less back to what is started as but all the crystals are aligned by cohesion. The addition of sand in correct proportions induces crystallisation and gives 'adherence qualities' It also gives it bulk, reduces shrinkage and saves on costs. Mortar MUST be kept moist during this crystallisation alignment process, and dry bricks should be dunked in water before laying to avoid sucking the moisture away before the process has completed.

Excess moisture then evaporates away by exposure to the atmosphere.

Hydraulic limes have unusual peculiarity of setting without exposure to air, and are thus very suitable for damp conditions.


Sand is very important, the properties seriously affect handling characteristics and finished strength.

Builders sand is a 'soft sand' and totally unsuitable. What is needed is a well graded clean free from impurities 'sharp sand' i.e. with angular edges, with proportionate sized grains, neither too fine or too coarse, to give the necessary texture and lock the mortar together.

Sharp sand is usually pit sand. Dredged sea-sand has rounded grains and is known as soft sand.

Mix Proportions

These were specified in the Ministry of Health Model Byelaws Series IV (buildings) and the typical proportions were :

  • High Calcium Lime (lime putty) 3 or 4 parts sand : 1 part lime
  • Magnesian Limes 2 or 3 parts sand : 1 part lime
  • Hydraulic Lime 3 or 4 parts sand : 1 part lime
  • Eminently Hydraulic Lime 2 or 4 parts sand : 1 part lime


By Matthew Marks 17/5/1999

The Problem

In our eagerness to slap up insulation everywhere, the potential problem of condensation is sometimes overlooked. Air can hold a certain amount of water vapour, and the higher its temperature, the more vapour it can contain. Air in houses in winter often contains more moisture (from breathing, washing, cooking, etc) than the cold air outside can hold.

Thus, if you insulate a surface but do nothing to stop vapour penetration (and things like plaster, wood, brick, concrete, mineral wool, and even expanded polystyrene allow vapour to penetrate easily), you may get a problem. This is what happens:  

       |               |                              |
temp.+++               |                              |
       | +             |                              |
       |   +           |                              |
       |     +         |                              |
hum. *******   +       |                              |
       |    *****+     |                              |
       |         **X** |                              |
       |             +*****                           |
       |               ++++*+*+*++                    |
       |               |        **+*+++++++++         | 
       |               |             *****   ++++++++++++++
       |               |                  *****       |
       |               |                       *****  |
       |               |                            *******   
       |               |                              |

The above attempt at ASCII art (if it *really* doesn't make sense change to viewing in a 'fixed width' font such as Courier) shows a cross section through an insulated wall, with temperature and absolute humidity graphs superimposed. The temperature and humidity each side of the wall are those of the atmosphere on each side. Although the temperature inside is higher than outside, the humidity line is below the temperature line at each point, representing less than 100% relative humidity - i.e. humidity relative to the maximum amount of water vapour the air can hold at a particular temperature. 

The insulation retards heat transfer better than the wall behind, so the temperature drops much more quickly within the insulation than within the wall. However, the insulation and the wall are equally vapour permeable, so the absolute humidity drops linearly. At point X, the two lines cross - at this point in the insulation the air gets too cold to support the amount of moisture it is carrying. In other words, dew point (100% relative humidity) has been reached, and condensation will occur. At this position it is known as interstitial condensation, and will saturate the insulation, rendering it less effective. More seriously, it may cause rot in any supporting timbers. It is particularly bad in this location because there is no ventilation to remove it quickly when conditions are more favourable (less absolute humidity and/or higher outside temperature.) 

The Solution

The solution is to put in a vapour barrier, like polythene sheet or a foil backing to plasterboard, to alter the profile of the vapour concentration through the wall. You will then get something like this:

INSIDE #| INSULATION    | BRICK WALL                   | OUTSIDE
       #|               |                              |
temp.++++               |                              |
       #| +             |                              |
       #|   +           |                              |
       #|     +         |                              |
hum. ***|       +       |                              |
       *|         +     |                              |
       *|           +   |                              |
       *|             + |                              |
       *|               +++++++++++                    |
       *|               |          +++++++++++         | 
       *|               |                     ++++++++++++++
       *********************                           |
       #|               |   ********************       |
       #|               |                       ************   
       #|               |                              |

The step change in humidity caused by the vapour barrier (symbol #) has made sure that the relative humidity is well below 100% throughout the wall. The vapour barrier is not assumed to be perfect (it will have joins, nail holes, etc), so the absolute humidity just behind the vapour barrier is still a little higher than outside, but an imperfect vapour barrier is usually good enough in most circumstances. 

Note that the position of the vapour barrier is very important: it has to be on the warm side of the major insulating element. If it is on the cold side, it will make matters worse by maintaining higher humidity through the insulation. 

As has been mentioned, the problem of condensation is worse if there isn't good ventilation to blow away the vapour when conditions allow it to evaporate, such as in insulated walls, where a vapour barrier is essential. However, you can usually get away with insulating the floor of the loft if there is good eaves ventilation and the insulation is baked regularly when the sun shines. But if the loft is boarded, any condensation will take much longer to evaporate. It is thus a good idea to place a vapour barrier underneath loft insulation in these circumstances, especially over humid areas such as bathrooms. Foil backed plasterboard is ideal, but strips of polythene between the rafters will do some good. Don't loop it over the rafters or it will be on the cold side of the insulation at some points. If the loft becomes a heated habitable room, the problem is transferred to the insulation above, because that is where the temperature gradient occurs. For the same reason, condensation between floors isn't usually a problem, and it is rare to have air bricks to allow ventilation. (Air bricks below ground floor level are to allow damp rising from the ground, as well as humidity from above, to be dispersed.)


By Matthew Marks 18/5/1999, with input from Stuart Grant

Ceilings and stud partition (i.e. not solid) walls were made out of lath and plaster before plasterboard was invented. Laths are thin strips of wood which are nailed between supporting timbers, separated by small gaps. When the laths are plastered, the plaster is squeezed between the laths and the resulting "nibs" hold the plaster in position.

Over the years, these nibs can break off (due to movement of the ceiling or disturbance from above), and the ceiling can start to sag. It is also possible that the laths become detached from the supporting timbers (usually due to the nails rusting if the structure has been damp). 

If a ceiling is bulging due to nibs breaking off, it can be repaired, if you have access from above. Hoover out any debris from between the laths and the sagging plaster (which may be easier if you cut out a lath), then carefully prop the plaster back into position with a large board, so that the load is evenly spread, and find some way of maintaining the board in position. Apply PVA glue liberally from above, diluted one part glue to three parts water, and remove the props 24 hours later.

It is also possible to glue laths back to joints using liberal amounts of undiluted PVA glue between laths and joists before propping the ceiling back into position. Nailing the laths is likely to damage the plaster too much.

If the ceiling is particularly bad, you can either remove it and start again, or plasterboard over it. Removing ceilings is a horribly messy job and, if you remove the laths too, you will have to take away any loft insulation first; but you will not lose any height when you install the new ceiling, and it may be better if you have coving.

It is best to screw rather than nail the new plasterboard in place. Nailing is less reliable, causes more disturbance (to the house as well as its occupants!), and is not much easier if you have access to an electric screwdriver. Special plasterboard screws are designed to hold the board firmly, if you take care to tighten them flush but not to break through the paper surface. They are available long enough to pass through an existing ceiling. It goes without saying that the fixings should be into the joists, not the laths!

Plasterboard is available in taper-edged form, where a small area along the long edges is thinner. If the fixings are in this thinner section, then the joints can be taped (with plasterboard tape, which prevents cracking of the skim coat) and the area filled with a skim (top) coat of plaster to give a good finish. The short edges are parallel with the joists, and the board is cut to coincide with them, preventing any movement here, although making finishing to a high standard tricky.

Alternatively, standard plasterboard can be used, the joints taped, and the whole ceiling skimmed. It is a good idea to use foil backed plasterboard in upstairs bathrooms, to reduce the possibility of condensation in the roof space. Ordinary plasterboard should be mounted with the "bad" side (where the joins between front and back paper are) downwards if it is intended to skim the whole surface, because plaster sticks to this side better.

Most DIY-ers are of the opinion that plastering large areas is best left to the professional.

Editors note: Also try an advanced Google search. Click on this link to search uk.d-i-y for ceiling and (cracked or repair or repair or sagging or loose) excluding (artexing or fan or stipple). Note that Google allows a maximum of 10 items in the search fields.


By CliveE 27/8/1999, summarising several uk.d-i-y articles from various authors.

The problem: 

It is generally easy enough to install a cat flap in a panel of a solid wood door but how do you do it if the panel is double gazed?

  • The bad news: the glass is very likely to be toughened (it should have an indication of such etched into one corner) and so there will be no chance of cutting it. The panel should not be replaced with non-safety glass which can shatter into extremely dangerous daggers.
  • Double glazed panels are usually only cut for a cat flap at the time of door manufacture. However, you may be able to get a new double glazed panel professionally made up with a hole in it, to replace the existing panel.
  • If you have a double glazed door that has two separate glass sections, one top and one bottom, you could replace the bottom one with an opaque plastic panel of the same thickness, available from a plastics warehouse or a double glazing firm. The standard construction is two hard plastic sheets with a foam fill inside, and easy to cut a hole in with a jigsaw. Larger plastic panels may be reinforced with an internal steel sheet and consequently more difficult to cut.
  • Some cat flaps are designed to fit into round holes, specifically for fitting through glass, but choice may be restricted to non-electronic types only. Flaps with square holes are generally for fitting in wooden or plastic doors. Some of those with "U" shaped flaps can fit square holes or large round holes.
  • Cats don't mind jumping a reasonable height to get in and out, and it may be easier to replace the glass in an adjacent small window than in the door.
  • Consider putting the flap into the garage back door or wall, or into the garden shed.
  • Make a cat tunnel through an adjacent wall, possibly under a work surface.

General Tips:

  • For security reasons, make sure any cat flap is well away from door or window catches.
  • The cat flap should be well draught-proofed.
  • A magnetic or electronic cat flap may help prevent other cats getting in and nicking food or marking their territory. This may mean your cat has to wear a chunky magnet on its collar but it will get used to that.
  • Steel doors or steel reinforced doors should only be modified at the time of manufacture.
  • Fit a small dog flap for big cats!
  • Whatever type of cat flap you buy, make sure it is suitable for the thickness of the panel you are mounting it in.
  • If making a cat tunnel, make it 5cm taller than the opening of the cat flap (with the extra at the bottom), to avoid forcing the cat to crawl through it or getting its paws caught. The hole in the wall must be lined to avoid contact with thermal insulation and to avoid heat-sapping draughts in the cavity. Stitch drill out bricks and use quarry tiles, varnished WBP ply, terracotta flue liner, or aluminium sheet to form a wipe-clean tunnel. Fit flap on simple frame externally with portcullis arrangement internally.

Tunnel Tips from Nightjar: 

One thing to watch out for is that the idea of a cavity wall, even if filled with insulation, is to isolate the inside skin from the outside skin, to keep the rain from penetrating. It would be a good idea to put an waterproof covering, like bitumen damp proof course material, over the tunnel where it passes through the outer leaf and carry that through the cavity, turning it up inside the inner leaf for about 150mm (6"). If you can make it wider than the hole for the tunnel, carrying it out about 50mm (2") either side of the hole in a mortar bed, and hang it out of the wall about 13-15mm (1/2" - 5/8") to make a drip edge, so much the better. For similar reasons, it is better to slope the tunnel floor down by a few degrees as it passes through the outside leaf. A piece of rubber mat glued to the floor of the tunnel should make it easier for the cat to get a grip.

Tunnel Tips from geoff

I built a cat flap into a wall which is 9" (i.e. one brick width) square and runs through two courses and the void. I would suggest one cat flap would be better than two - apart from the price, the cat won't feel trapped inside a box, and it will be easier to train it to use the flap - once it nudges the door in either direction it can see the outside world. I put a piece of mineral damp course immediately above the cat flap housing to add a bit of protection against rain. I built the tunnel out of plywood to which the cat flap is attached, and mortared it into the wall. I actually built the wall and integrated the cat flap into it.

Tunnel Tips from Phil Addison: 

I just measured the height of my cat and made tunnel to suit. OK, he had to stoop a bit! There was an additional complication in our set up - no free outside wall space. I solved this by putting the tunnel right through one of the fitted cupboards as well as the wall. This entailed a second cat flap let into the cupboard door. Moggie needed the usual training of passing through it with the doors tied open for a few times before she could manage the closed flap. There was one snag I hadn't thought of: we have a couple of steps down from the kitchen door, and the kitchen units have a 6" plinth, so moggie emerged [outside] about 3' above ground level. No problem getting out but she couldn't get the hang of taking a flying leap at the closed flap 3' up the wall to get back in. I fixed a shelf just below the flap for her to jump onto.

The electronic type of flap has one nuisance problem: if the cat lingers near the flap the mechanism can go into oscillation and make an objectionable repetitive clicking. What happens is the cat slowly approaches and the solenoid activates with a 'click'. That startles puss who pulls back and the solenoid deactivates making another click. Puss then leans forward for another attempt and the cycle repeats. This can go on for 1/2 min. or more while puss makes up its mind to come in or not. The electronics really needs a delay circuit to prevent this.

Another thing I found in the investigation is that the cheaper ones are battery operated, and I suspect drain fairly quick. Mine is transformer operated. There are also magnetic versions that have no electronics. I tried one and was unimpressed with its effectiveness.

By the way, check if your door panel has a thin metal sheet sandwiched in it - many have. It reduces the sensitivity (a lot) to the magnet, and Staywell say it's 'not recommended'. Nevertheless, we got one to work OK by moving the receiving coil to the extreme outboard of the housing.


Cormaic: The only sure way is to replace the blocks. My web pages illustrate how to do it (see http://www.pavingexpert.com/) Take an old block to a builders merchant to get a match.

There are special oil patch removers on the market - none is particularly effective unless it's a very recent oil spillage, but their performance is improved if washed with a power washer after each bout of cleaning.

If this is likely to be a recurring problem, you may wish to consider one of the better acrylic sealants, which 'varnish' the driveway, protecting it from oil and the like, but imparting a glossy finish. Again, there is more about these sealants on the above web-site.

Other suggestions from various authors:

  • Liquid detergent and water.
  • Paint brush cleaner. (Richard Gethin)
  • Soak-up using cat litter on it, cover it to keep it dry, leave it for a few weeks, shovel it up. (Tony Williams)
  • Sprinkle dishwasher powder (or crumbled tablets) over it , damp it down with a watering can then leave it for the rain to wash away. (Stuart Grant)
  • Or even normal (clothes) washing powder and a bit of hot water. (Graham Anstey)
  • Make up a paste of bleach and Fuller's Earth, and butter it on. For getting stains out of a badly-sealed stone kitchen worktop, it was pure magic. (Mike Barnes)
  • I've had some success on brick with Gunk followed by a high pressure washer with detergent. (Peter Parry)
  • Use Jizer! Brush on, let it soak in, then wash off. Whilst it's wet, sprinkle washing powder on it. (Dave Goulbourne)
  • Pour laundry detergent on the stain, followed by gasoline, and scrub it with a hard bristle brush. Then wash it down. (Steph Greenberg)
  • Unless your son has dumped a whole sump full of oil onto the driveway, I would not bother to do anything about it. Most driveways have the odd oil stain. They are almost inevitable and are nothing to be ashamed about. (Colin Bignell)