I don’t know about you, but if the sun shines I feel much better. I seem to have more energy and once I arrive home I no longer collapse in the chair with a beer but have actually been known to walk the dog! All 14.5 stone of me!
Along with the sunshine we could do with the heat of the sun on our backs and as I sit and write this, the forecasters have said the week is warming up and that by the weekend we will have summer on our hands. I confess to being on leave in a fortnight’s time and I would like that sun to shine since it will be a staycation rather than jetting off to warmer climes. I bet that within a few days we will all be saying “it’s too hot” and “I could do with a breath of fresh air”. Funny lot aren’t we?
VENTILATE
A roof I went in earlier this week could have done with a breath of fresh air. The property was newly constructed and so there weren’t any problems to speak of but if something hadn’t been done there surely would have been within a relatively short period of time.
It’s unusual these days to see anything other than breathable membranes on a roof. I like these a lot, despite being a traditionalist at heart because they make the system of building much easier, no more having to ventilate the roof voids through soffits or over fascias and therefore when you come across something more unusual you have to try hard to think of what the requirements used to be. Breathable felts are fine as long as they are supported with tilting fillets as they do deteriorate over time at these junctions. Eaves vents are equally fine but there are other matters which impinge on this form of construction of which you should be aware.
Now back to the earlier roof. I was surprised to see a type 1 hessian based felt in use and when I asked the builder he quite rightly said that if it was on the specification it would be what was used. With these roofs you have to be aware of the need to go back to more traditional forms of ventilation and therefore in this case soffit vents were installed in the form of pre-cut upvc units giving an equivalent 10mm gap all around the perimeter of what was a hipped roof.
PREVENT CONDENSATION
It was inside where the trouble began. The 300mm fibreglass insulation provided was neatly laid, don’t get me wrong, but almost too neatly as it was nicely tucked down into the eaves. This is fine if you are using breathable felts but not so the old, more traditional methods of construction. Who remembers the plastic eaves trays then? Pre-formed units nailed to joists which maintain an air gap where the void becomes tight between rafters and the eaves construction. This simple tray allows a through flow of air into the roofspace across the top of the insulation so vital to prevent condensation forming on any structural members or the underside of the felt.
Guess what? The builder had not installed them and so the net result was despite everything being in place the roof had no through flow of air. If I’m honest I really didn’t fancy the job of removing the insulation and providing the free flow but some poor soul would have had to do it!! I bet the sun wasn’t shining for him!
See you next time.
