is efflorescence in roof timbers worrying or not ?

Hi there Efflorescence is not found in timber it is usually found on bricks tiles or stone products & is a result of the salts & or potash being drawn out by the evaporation of moisture in the product as the moisture evaporates crystals are left on the surface & since timber does not have salts or potash in it it is very unlikely this is efflorescence you can see unless it has dripped on from some other surface hope this is of use to you Andy Acorn joinery & building

Hi, Timber doesn't usually suffer from efflorescence, unless it's againts damp brickwork/stonework which is causing it. If it gets worse, this would indicate either a leak/damp somewhere or the roof just needs ventilation, because the humidity is too high. It sounds more like the beginnings of dry rot to be honest, the fungus dies off as the humidity drops (although it can lay dormant). If it gets worse then call in someone, if not I wouldn't worry, the timber/roof has enough ventilation and has already naturally dried out enough for it not to grow. What ever it is... If you mark the edges of it with a marker, Keep your eye on it after wet weather etc. Hope this helps Nothing bad will happen quickly,(this happens on new build roofs that have got wet, even treated ones) when they were fitting the roof...it can take a while to dry out. The damp/timber survey should be able to put your mind at rest :) may just need treating(if it isn't already) to be on the safe side in case of future leaks etc.

When the roof was renewed did they fit vents to eaves and at high level, you need a good circulation of air in the roof space. If no vents you can fit tile/slate vents.

Was the new roof in 2004 a straight forward re-tile or were the rafters also renewed? If original rafters, then treatment would be highly recommended. If rafters were replaced they should have been treated already. If this is a case of Dry-rot ( Serpula Lacrymans) then no amount of ventilation or timber treatment will eradicate the fungus. Brickwork can be treated if dry rot spaws are present, simply hacking off the plasterwork to a minimum 1.2mtr from last infected visible area, chemical treatment with Netcem35 rendercoat applied. However with timber, the only solution is to remove the timber altogether and renew. Unfortunately, with Dry-rot it requires moisture to remain active, all timber will have a certain moisture content. Once Dry-rot is present in timber such as structural timbers (rafters). Infected timbers are generally brown,dry and brittle with cuboidal fractures and can be crumbled by hand.Usually it would require 20% or more moisture content for the spores to germinate, so if you have had a leak in the roof area, or there is an obvious lack of ventilation to the roof void, then yes this would produce an ideal enviroment for the Dry-rot to spread. A severe case has the potential to spread at a rate of 12" p/month. So you should act quick if this is Dry-rot. If this is the case, my advice would be to remove infected rafters, replace with new. Check for any potential leakages on roof and gutter line, repair these and then improve ventilation to roof void as much as possible.