I asked a question about lime render and s/s expanded mesh a few weeks ago,= as I'm replacing the exterior render between two bay windows, which is woo= den studwork really.
Now a new problem. The bell cast at the bottom was formed by a triangular p= iece of wood, about 70mm by 45mm. It wasn't too bad after 75 years but ther= e was a bit of rot along the edge that the render and mesh sat on. So, I de= cided to replace it.
First, it turns out that only heartwood is rated of any durability at all i= n constructional purposes (BS EN 350 rates all sapwood as durability 1) but= after rejecting what was on offer at B&Q as having no visible heartwood at= all (no darker wood towards the centre of the growth rings) I found pine t= hat was mostly heartwood at a local timber merchant and was all heartwood a= fter I'd sawn it to shape.
Next problem: the wood that used to form the bell cast probably, looking at= it, was Douglas Fir/Columbian pine (reddish). This rates slightly higher i= n durability (3) over what the local timber merchants offering is - pinus s= ylvestris I think, (Scots pine/european redwood/red deal, all different nam= es for the same thing), durability group 2/3.
In any case softwood, even the heartwood component needs preserving for a d= ecent service life, so I've painted on three coats of Wickes clear timber p= reservative. Even so, I'm still in a quandary, it's not exactly pressure tr= eatment, is it? I'm going to give it a few coats of bituminous paint in add= ition (literally, tar in paraffin).=20
Do people think this enough? Am I worrying too much? Should I bin the wood = idea and use a s/s mesh bellcast?
Oh, one more thing. The wooden 2" x 3" vertical studs inside the bay cavity= are all dangling 3-4mm above the (teak) horizontal beam below, except the = two studs at the ends. They were skew nailed on to the (previous) window be= low once upon a time, but although the skew nails are still in the studs, t= hey have been sliced off before they enter the beam below, presumably when = the 1970s windows were put in. This can't be right can it? I have cut thin = wedges and banged them into the gaps between the vertical studs and the bea= m beneath, should I restore the skew nails too?