Severe Woodworm Infestation

[GPHouse]

I've finally just got in to a new house which is about 230 years old.

It's been sat empty for nearly 2 years and was abused for 20+ years before that and in the process of stripping it back (destructive creation) I have uncovered severe woodwork in approximately 1/3 of unexposed timbers including a good few DeathWatch infestations.

I need to balance long term die off with a kill everything that moves RIGHT NOW mentality

I'm looking at treatment paths and have asked some specialists questions they can't answer....

I'm going to use a mix of boron and Permethrin sprays and pastes, and will probably put some boron rods in too.... but.

Step 1 - Boron on all timbers (spray)
Step 2 - I'm intending on injecting and drilling in Permethrin where I have severe infestations
Step 3 - I intend to then inject and drill in Boron in key sites and where the infestations are... How long should I wait before doing this and do they Permethrin and Boron pastes react at all?
Step 4 - Continue replacing timber where required, treat and insert boron rods.

Also, re Permethrin options, do solvent based options penetrate better than water based options?

Any pointers on how to best start a long term plan of treatment following an initial genocide attempt would br gratefully received.

Thanks
G

 

[malcolm]

The first 5 posts are delayed a bit so here is a bump to the top.

Beetles like damp wood so the long term plan must be to make sure the wood stays dry. That means getting rid of modern waterproof paints and any cement against the wood and ensuring ventilation, but it sounds like you are on top of that.

I can't really advise on treatment as my beetle infested wood had been mistreated for a lot longer than 20 years and had to be replaced. The woodwormed floor boards aren't badly damaged and I'm doing the heating and ventilation thing with them, so no need to treatment here. I would be careful of taking advice from the people who treat this sort of thing as there seems a lot of misinformation from people with a sprayer who want to make some money. Though I can sympathise with a kill them until they are really dead mentality.

 

[MatthewC]

Matt Green is our wood beetle expert - hopefully he will be along soon! In the meantime, get the house dried out as I agree that helps in the long term.

MatthewC

 

[GPHouse]

Thanks - would be interested to hear what Matt has to say...

We're doing all we can to dry the place out and treat - new breathable felts just gone on some of the roof - the rest to follow when the weathers bearable (and we have funds), cement plaster is being removed, plaster board is being removed and we're exposing as much of the wordwork as possible to let it air...my dehumidifiers going into overdrive...

I'm contemplating devising a way to heat the floorboards to 55-60d egrees to treat them pre Boron spray... could be an easy enough project unless anyone knows of a cheap way of doing this?


KR
G

 

[Matt Green]

I'm going to use a mix of boron and Permethrin sprays and pastes, and will probably put some boron rods in too.... but.

Step 1 - Boron on all timbers (spray)

Will not penetrate far at all and do flat nothing against death watch. Boron is a furniture beetle 'lifecycle breaker'. Apparently. It works by killing first instar larvae, which have the biggest surface area to volume ratio. There is a bit of a lack of data on this. Boron is not going to be supported through the European Biocidal Products Regulations.

Step 2 - I'm intending on injecting and drilling in Permethrin where I have severe infestations

Use a paste. It will do less damage to the timber than drilling them. Drilling is also likely to remove move timber than the insects have.

Deepkill paste* (ai: Permetherin) Sovereign chemicals:
http://www.sovchem.co.uk/timber-preservation/active-infestations/environ-deepkill-timber-paste.html

ProBor20* (ai: Sodium octoborate) Safeguard Europe
http://www.safeguardeurope.com/products/probor_20

*both of these products are due to be withdrawn from the market in April 2016. It is unclear which like-for-like replacement use products will be available past that point.

Step 3 - I intend to then inject and drill in Boron in key sites and where the infestations are... How long should I wait before doing this and do they Permethrin and Boron pastes react at all?

No, they don't. But, again, I would use pastes. Really: the concept of boring into timbers with 10mm bits to inject insecticides to prevent 4mm insects emerging is bizarre. Stop the water, remove the impervious finishes, apply insecticides to areas with highest risk of further immediate damage and wait for the structure to dry down.

Step 4 - Continue replacing timber where required, treat and insert boron rods.

Also, re Permethrin options, do solvent based options penetrate better than water based options?

Boron rods are only useful if you can't stoop the water ASAP. Money is always, always, better spent stopping the water. Solvent carrier fluids have better penetration, but are best used sparingly.

Take a step back for a moment and dispassionately separate the damage you can see from the risk of potential damage from insects that may still be in the timbers. I think your money is probably best invested in paint/varnish/lacquer stripper and roofing works at this point. That done, the insects will take care of themselves.

First step, strip the finishes back from the worst affected bearings, apply paste until the weather improves and you can get to the roof and rainwater goods.


Matt

 

[GPHouse]

Hi Matt

Thanks for the swift reply.

We've been owners of this property for 3 weeks but it;s been 10 months in the planning so we're well into the process of making good.

- Breathable felt is now in place in the worst areas and we'll be doing the rest in the summer (but those areas are pretty good atm to be honest).
- Ventilation is now sorted
- We have heat throughout and dehumidifiers are running in worst hit areas
- Paints and finishes are being removed and to save myself going though Klingstrip /Nitromors hell i'm getting a soda blaster in.

I'm surprised by your comment on Boron and Death Watch but noted, nasty permethrin it is for that in paste format!

Unfortunately, sitting back dispassionately I still need to get the beetle problem sorted as it's so widespread (death watch and common furniture) and given the long term abuse this property has undergone, and how close some of the structural timbers are to being unrecoverable, I have to go on a bit of a pogrom.

Some wall plates and lintels I have uncovered are literally dust/ a fragile wood lattice - structural collapse has been narrowly avoided!

With respect to the paste, some of the beams are and will remain open - can you recommend a deep penetrating treatment other than drilling / injecting for those as its my understanding some of the pastes tend to mark the wood (eg Wykamol)?


KR
Gavin

 

[Matt Green]

Hi Matt

With respect to the paste, some of the beams are and will remain open - can you recommend a deep penetrating treatment other than drilling / injecting for those as its my understanding some of the pastes tend to mark the wood (eg Wykamol)?

Hi Gavin,

Yes, they can leave tide marks. The bearings are the high risk areas, exposing and treating them is a good option. Full exposure and isolation would also be good, if possible and safe to do so. Tent off sections of wall with embedded plates and dehumidify or place a cold air blower facing the worst effected sections.

A micro-drill survey might help you assess the risk and the condition of embedded bearings.


Matt

 

[malcolm]

Do you have ventilation in the roof space? There is a myth going around that breathable felt is OK without additional roof ventilation, but even building regs* insist on at least eaves ventilation in older buildings when using breathable felt because of likely air leakage to the roof space. New buildings aren't required by regs to have the ventilation because every component of a new building will work perfectly for hundreds of years.

*I think the master plan of building regs is to reduce CO2 emissions by using their legal powers to make old houses fall down as soon as possible thus reducing their emissions to zero. They seem to want new houses to fall down even more quickly, but that seems fair.

 

[GPHouse]

Hi All

I will definately expose them, dry and treat.... I have a couple of joists I'm a little concerned about - some sponginess around the timber going into the socket.

Re the roof...Hope this makes sense (see attached image)


The roof is in 2 parts, the main roof is a typical A frame, with a second set of rafters at a lesser angle coming off the A 3/4 of the way down to a lower wall (the property is stepped) which will as of this week be vaulted a roof - there was a rudimentary ceiling in place but it's been removed to allow access to the beams. There is also a flat roof dormer coming off this....

The typical A roof void has open eaves (now that i've removed a few tonnes of straw which had been stuffed into them over the years) and a variety of ventillation points, some deliberate, some not - this is still bitumen and I will replace that at some point but it's in good condition atm and the main timbers are mostly fine. There is no insualtion at the moment - pre beetle spraying

The lower roof how has breathable felt and no board or insulation at all below it at the moment.

There eaves of the original A frame on the inside of the house currently run under the newer roof space (still v old) and there is one hell of a gale running though the house!

My intention is to:
- Treat the timers throughout.
- Replace where required
- Block the eaves between the two sets of rafters loosely with thermafleece or somrthing breathable
- Use Thermaflece in the standard loft space and keeep the eaves open plus look at some othe ventillation in time + Breathable felt
- Use Thermafleece or similar breathable insulation in the vaulted ceiling, keeing an airgap - and where possible keep the eaves open - not possible above the dormer

In terms of boarding the aulted roof - I still have no idea what product to look at. A specialist told me to use Fermacell but it's massively heavy and as far as I can tell not breathable!?

KR
G

 

[malcolm]

Fermacell looks like modern dry lining. I'm trying to avoid anything non-breathable - any warm air leakage from the house or changes in temperature outside could condense on the cold side and run down, keeping your wood nice and damp. I had this in a garage once. The garage wasn't heated but water would drip down the back of the celotex onto my work bench in the winter.

I'm subject to building regs here so have used some non-breathable materials - 150mm (6 inches) of celotex in places as the alternative would have been 300mm+ (12 inches) of natural materials. Where I've done that it is only in areas where the cold side is accessible for inspection. I've used tape to reduce air gaps as far as possible and made sure the cold side of the insulation is very well ventilated.

If you need insulation then woodwool board could be a possibility - needs to be about double the thickness of celotex for the same insulation but will breathe, controlling moisture. Ty Mawr has a fair range of boards useful for research: https://www.lime.org.uk/products/boards-and-backgrounds/ I'll probably take the hit on space and use something like that for the solid walls downstairs.

I wish I had used Thermafleece. I went for mineral wool and it is horrid dusty prickly stuff, and just for that reason I ought to have gone another £1k on the sheep wool. Still haven't finished the loft insulation.

Keeping everything dry and well ventilated is definitely the way forward.

 

[a twig]

There is a myth going around that breathable felt is OK without additional roof ventilation, but even building regs* insist on at least eaves ventilation in older buildings when using breathable felt because of likely air leakage to the roof space.

There's a bit more nuance to it that that - some more detailed and helpful guidance here:
https://www.charnwood.gov.uk/files/documents/breathable_felts1/Breathable felts.pdf

 

[MatthewC]

I wish I had used Thermafleece. I went for mineral wool and it is horrid dusty prickly stuff, and just for that reason I ought to have gone another £1k on the sheep wool.

I used Thermafleece and am convinced it is one major reason why my house is so warm. As I go up the stairs, I can feel the increase in air temperature, so I am sure that very little heat goes through the ceiling into the ventilated roof space. Well worth the cost, and much nicer to work with!

 

[GPHouse]

Thanks for the advice,

Permethrin stuff from Sovereign in, some Boron stuff for less severe areas of common beetle on the way

Useful advice and I'm definitely going for thermfleece, despite the fact it;s hugely expensive... unless anyone has any other suggestions? Also, anyone found any deals?

I'm opting for a combination of Cosywool and Ultra Batts in the roof.

I'm trying to do all of this with breathable materials, I'm still struggling to figure what to do with the roof - I'm not using L&P or reed matts, I want a simple solution.... Any thoughts?

 

[Zebra]

Have you thought about woodwool boards? I've used them extensively.

 

[GPHouse]

I have, and heraklith.

I haven't been hands on with them but I was contemplating using them as a plasterboard replacement as they are breathable unlike the likes of fermacell.

How did you find working with them? Did you plaster on top?

KR
G