Air and wood moisture ratio- woodworm.

[Safety First]

Re Loft space humidity and its bearing on the moisture content of the timbers therein.

*This* indicates that providing relative ambient humidity is <75%, the timbers will equalise to no more than 15% moisture content.
(Excluding leaks/ingress, and vapor entering loft through ceilings/around lights etc). Am I reading it right?

*
http://en.wikipedia.org/wiki/Equilibrium_moisture_content
*

Having just had a new roof:

Ancient pan tiles 'changed to' modern better fitting tiles without gaps/cracks.
Bituminous felt 'changed to' breathable felt.
Eaves fully stuffed with insulation 'changed to' eaves vents all round.
No vents in soffits 'changed to' vented soffits all round.

I found ceiling joists circa 15% moisture content on top, and around 11 % at their sides which were covered by insulation between joists. I expected reverse pattern as moisture laden air if coming up through ceiling would dampen the covered parts of the timbers, but not so?

Few areas with woodworm were all 19-21% moisture readings, apart from a few that are presumably old exits and inactive now..

1930's Semi & not a fan/believer of spraying BTW.

 

[foxhole]

Moisture in loft is from air movement thru it, none comes up thru you ceilings.

 

[Safety First]

....none comes up thru you ceilings.

Thanks foxhole...Indeed that is the aim, but many ask about condensation on these forums- I have been reading(!) and are told that to check that light fittings are sealed up, that loft hatch is sealing well, that cracks in ceilings are minimised.

Still wondering about the use of humidity meter, my links to the graph and the means therein to *know* (?) that the wood will eventually end up too dry for much woodworm activity....

anyone?

 

[foxhole]

Woodworm thrive whatever the conditions, had a piece of hundred year old oak in my garage three years thru freezing and damp conditons and then mounted it over hot fireplace where is became very dry and still had to treat it for live woodworm who had been dormant for at least three/four years.

 

[Safety First]

Woodworm thrive whatever the condition.

I doubt it, but nevermind.

 

[Flyboytim]

Generally, warm interior air is moisture laden, so you do not want it escaping into the loft on a regular basis. If there is warm moist bathroom air venting into an insulated (cold) loft, the cold surfaces will be likely to have condensation - brickwork, exposed timbers, and the underside of roof felt - even breathable microporous felts can get moisture beads on them, and the cold surface of the insulation material can become damp.

Condensation can cause drips which tend to be in the same place, causing wet spots.

The combination of plaster or plasterboard ceilings with insulation above is enough of a barrier in most cases.

Woodworm tend not to like old dry wood much, they like it damp with a little fungal decay which increases the protein content of their diet. They also cannot stand being frozen (infested antiques are sometimes bagged and put in the deep freeze for a week or so to kill off the beetle, eggs and larvae.)

If you generally do not have a damp problem as your post appears to show, you don't need to spray wholesale, but in those areas where you do have potential infestation, it may be useful to paint on a timber treatment that treats both fungal and insect damage.