Managing/recovering from woodworm - a guide!

[Whitling2k]

Hey all,


I just thought I would write a post after my recent journey against a fairly severe woodworm infestation.. I’m not all on the mend, have almost completed my renovation and things are on the up after discovering the little f**kers eating away my house.


Firstly, if you go professional, I would recommend keeping the spraying to sprayers and the building to builders.


A general builder might not understand woodworm and the treatments enough to do a thorough job of getting rid of them and might wing it. A dedicated sprayer will know what to do with the insects, but might not be best placed to repair the rest of the house. It might be a bit more expensive, but you will have more peace of mind.


We used a local sprayer who came recommended and also had presence on the web did all the prep & repairs ourselves - combining it with a larger renovation.


Anyway – here are loads of things I learnt on my way - it’s a very winnable problem! Sorry if I’m coming across as a bit condescending - I don’t mean to be... but - Some tips might help - hopefully organised in a slightly useful way. If just one person reads this and feels better or less worried after putting their foot through a floor or stair case, I’ve done my job. It’s also a way to give something back to this excellent community!


I have learnt all this from reading, the web, speaking to experts, trial and error and my own observations (I’m a scientist!). I just can’t remember where all my references should be, it’s 2 years of accumulated knowledge – so feel free to point any errors/omissions.


Whitling2k


Try understand the scale problem before your get a survey/quote

• The worst of the damage is likely to be where the wood can be damp (>~20% saturated)
• Most internal infestations are in ground floor-floor boards, in and around bathrooms and other wet/damp spaces, attics & roof spaces, unvented spaces with moisture (such as under stair cupboards) & sub-floor joists & noggins. These are the key spaces to check.
• Check inside your timber framed walls, behind any panelling, hidden timbers etc. If you can get hold of an endoscope, then do! You can drill a small hole through your plasterboard, inspect then fill if there is no damage. It’s easier to rip it off now than get it sprayed & repaired and then have to start again because your internal stud walls start to come down.
• Live infestations will produce ‘krass’ which looks like saw-dust. An active infestation will be obvious because crass will keep reappearing. Try a sheet of white A4 card under a suspect timber to help spot it.
• They are most active April-September - which might be when you see the live beetles.
• Know your enemy! The most common culprit is the common furniture beetle - which is not actually a worm. They lay eggs in exposed, damp (20% and above) timber. The eggs hatch, and their larvae eat into the wood, and spend 3-5 years+ boring their way through it. Then, they move to 1-2mm of the surface where they pupate and turn into hard-shelled little brown flying beetles. These then burst through the surface of the wood, producing the 1-2mm round circular holes. The beetles don’t actually eat anything - they exist just to mate.
• I would recommend getting a few quotes - compare what each say - ask around, especially on here, if you have any questions.
• Bigger national companies are definitely worth getting in for a quote, but they do invest far more into advertising and the whole “customer experience”; their sales folk are all very savvy, but they people they get round to do the job are a bit more questionable(so I hear).
• Woodworm are actually less common on the relatively dry east of England than the damper West, and they prefer lower-laying areas. We therefore have fewer firms this side of the Pennines.

before - treatment

• Rip as much wood out as you can safely remove and burn it or take it to a skip
• Anything you can’t take out, spray.
• When you get your floors sprayed - make sure you clean them as well as you can before the sprayer comes. Especially the lines between the floor boards. The chemical (whether boron or permethrin) will just soak into decades of carpet dust and not your timber otherwise.
• Same also applies for anything on top of the boards - i.e. old lino floor adhesive or varnish.

Treatment

• The best price is not necessarily the best contractor! You need one you like, one who appears knowledgeable and one who doesn’t give the hard-sell
• Successful treatments interrupt their life cycle, they don’t usually kill it outright, just stop its life cycle from completing.
• The spraying will only work on exposed timber.
• See if the contractor will leave some chemical behind so you can treat any timber you expose during follow-on repairs, after the contractor has been round.
• If they won’t or you need more, woodzone is the concentrate formula I used for resprays. I apply it from a modified plant sprayer (to reduce misting, it’s a direct jet now) AND PPE UP!
• Ignore the cloud or fogging techniques - they only work where they can get the fog or mist to sit on a timber long enough to transfer the chemical. How often does a room fill completely with steam? During an hour long bath? Your spray technician gets paid for the job, not by the hour! Will they wait until the fog has filled every last complex part of your underfloor? A spray jet will be far more likely (with the right sprayer)

Repairs & after treatment

• If it’s a small section of your joist that has gone - you can try sistering in repairs. Cut the damaged section out (with supports if anything is resting on it), treat all exposed ends, slide a piece of wood of the same dimensions into the gap, then sandwich the new piece between two other bits also of the same dimension and extending a minimum of 1m beyond the removed section. Use heavy duty bolts & timber connectors to fix it all together. Similar if it’s the end piece - but slot one side of the repair into the hole in the wall.
• 22mm tongue and groove chipboard is makes a really solid floor if it’s done properly - more solid than floor boards.
• You can stick a screwdriver into effected timbers to see how deep the worst of the damage. If you can get the blade ½ to 1 cm in, and it’s a 4” joist, you will probably be OK - if you act quickly (i.e. in the next year or so)
• Don’t bring any plywood in! They like the glue, especially in older plywoods.
• If you replace carpet, try to spray the grips before they go down. Wooden carpet grips are made of cheap plywood!

Prevention (also useful for repairs)

• If you have a underfloor space, systematically check all of your air bricks - get a 12”or longer piece of metal (like a long skewer) and poke it in each hole in each air brick to clear cobwebs, dust, plants, slugs, dead mice ect! Be careful not to stab any live wires!!
• On a cold day, have a look under your floor - do you have any condensation on anything? Check more than once!
• Standing water in your sub floor space is not a problem IF it’s not touching any timber AND you have good ventilation through your air bricks.
• Could anything else be causing damp in the affected areas? Leaking heating pipes? Leaking flue? Condensation? Other ventilation issues (chimneys blocked?) leaking water pipes? Drips? Leaking roof? (We had a leaking roof, it dripped into a disused water tank in the attic, which then sent the water down some of the old pipes, into the ground floor ceiling, then along the top of the plasterboard, down the wall and it reappeared right into the middle of the house - 2 floors and 10m away from the point of ingress!! It can and does happen!!!
• Make sure all timbers are replaced with manufactured boards (MDF/chipboard), pressure treated timber or fully primed untreated timber (all sides and ends, even the ones you can’t see). Varnish will do the same if you can’t see it. I slapped a whole load of cheap varnish under our stairs, after they had been sprayed - locking in the treatment and reducing the risk of further infestation.
• In the particularly damp and badly affected areas, make sure to systematically treat the end-grain of any cut treated timbers with an insecticident end-grain preservative.
• Woodworm need food & drink to survive. Their food is the wood. Their drink is the dampness in the wood. Let it dry out and they will most likely go. It’s an urban legend that they can’t survive in a heated house - they can! However, manage your internal moisture & ventilation, and they will slow down enough to stop worrying about in the longer term