New build roof trusses. Treated or Not ?
Discussion
New build cottage. Trusses will cost £2500. Option of treatment at an extra £250.
Architect friend says yes.
Builder say no "waste of money"
Building control say can if you want but no need.
This is in Worcestershire so no nasty insects and detail of roof should be such there will be no condensation etc.
If it was £100 I might just do it but £250 is making me think. Any opinons / advice out there ?
DH
Architect friend says yes.
Builder say no "waste of money"
Building control say can if you want but no need.
This is in Worcestershire so no nasty insects and detail of roof should be such there will be no condensation etc.
If it was £100 I might just do it but £250 is making me think. Any opinons / advice out there ?
DH
You will find that architects always go way over on spec. I'm speaking from experience here! 
All roof spaces are well ventilated these days and roofing felts are also breathable, so any timber will be ok.
Can't you just give them a coat of wood preserver yourself before they felt and batten it?
All roof spaces are well ventilated these days and roofing felts are also breathable, so any timber will be ok.
Can't you just give them a coat of wood preserver yourself before they felt and batten it?
gtr-gaz said:
You will find that architects always go way over on spec... All roof spaces are well ventilated these days and roofing felts are also breathable, so any timber will be ok.
This is VERY VERY bad advice!!The insulation levels demanded by current Building Regulations have increased dramatically in recent years, whilst the cross-ventilation requirements haven't changed at all in my career (20-odd years in the industry).
This is a problem waiting to bite the industry in the arse IMO, and to be perfectly honest we've now reached a point where no matter how well ventilated the roof is it wont make a difference. If you use fibreglass insulation quilt, the depths required by the B.Regs are such that it is so absorbent that just the moisture condensing out from the air in the loft space itself on a night forms a 'dew' on the insulation that is absorbed and will never get the chance to adequately dry out in winter.
We (and other builders I know) had a spate of complaints during the cold snap late last year (where high levels of condensation coincided with people going up into their lofts to fetch Christmas decorations down, ironically), where the insulation was so saturated with condensation that most people thought they had a leak from the roof or water tank, and in some cases was bad enough to cause internal staining on the ceilings. And that's despite the fact that (at my insistence and extra cost, which doesn't go down well with my MD at the moment) we specify breathable roofing felt as well [eta: not all roofing felt is breathable, btw, it depends on specification] as the eaves and ridge ventilation.
This is something that afflicts all modern house builders (though none of us will publicly admit it, obviously) and which I've personally reported to the BRE; ultimately, the solution will have to be to use a form of insulation that doesn't absorb moisture (ie. closed-cell rigid foam) and/or to go to 'warm roof' construction, where the insulation is at rafter level.
In the meanwhile, do yourself a favour: get your roof trusses treated, whatever the cost!
Edited by Sam_68 on Thursday 4th June 18:50
Sam_68 said:
And that's despite the fact that (at my insistence and extra cost, which doesn't go down well with my MD at the moment) we specify breathable roofing felt as well [eta: not all roofing felt is breathable, btw, it depends on specification] as the eaves and ridge ventilation.
The benefits of breathable felt are questionable. They are fine in tests but what about when all of the holes are covered with dust and they don't get off to a great start since we've all seen how much dust is created on building sites.JR said:
The benefits of breathable felt are questionable. They are fine in tests but what about when all of the holes are covered with dust and they don't get off to a great start since we've all seen how much dust is created on building sites.
Yes I agree. It's better than nothing as a belt-and-braces approach where we're already providing eaves and ridge vents, though, is my attitude.Much like the permeable paving that the EA are insisting on everywhere these days. Fine for the first couple of years but the flash floods will be amazing when it's all silted up in a few years time.
There's some really half-arsed technology and detailing going into modern housing, mainly driven by 'Eco' legislation they hasn't been properly researched.
Sam_68 said:
JR said:
The benefits of breathable felt are questionable. They are fine in tests but what about when all of the holes are covered with dust and they don't get off to a great start since we've all seen how much dust is created on building sites.
Yes I agree. It's better than nothing as a belt-and-braces approach where we're already providing eaves and ridge vents, though, is my attitude.Much like the permeable paving that the EA are insisting on everywhere these days. Fine for the first couple of years but the flash floods will be amazing when it's all silted up in a few years time.
There's some really half-arsed technology and detailing going into modern housing, mainly driven by 'Eco' legislation they hasn't been properly researched.
As you point out permeable paving is the next idiotic idea; it'll just mean weeds in evryone's driveways, unless they pull them out, treat the blocks, fill the gaps with sand and seal the drive. Would be better to be honest and insist on a drain with a soakaway or forget the whole thing since half the time we complain about potential droughts.
JR said:
Sam_68 said:
JR said:
The benefits of breathable felt are questionable. They are fine in tests but what about when all of the holes are covered with dust and they don't get off to a great start since we've all seen how much dust is created on building sites.
Yes I agree. It's better than nothing as a belt-and-braces approach where we're already providing eaves and ridge vents, though, is my attitude.Much like the permeable paving that the EA are insisting on everywhere these days. Fine for the first couple of years but the flash floods will be amazing when it's all silted up in a few years time.
There's some really half-arsed technology and detailing going into modern housing, mainly driven by 'Eco' legislation they hasn't been properly researched.
As you point out permeable paving is the next idiotic idea; it'll just mean weeds in evryone's driveways, unless they pull them out, treat the blocks, fill the gaps with sand and seal the drive. Would be better to be honest and insist on a drain with a soakaway or forget the whole thing since half the time we complain about potential droughts.
The real problem is caused by local councils charging for what people used to get for free, the parking space outside your house. So, people put their cars on the front garden, realise it's gets muddy and unsightly, so pave it, and the water runs off into the street drainage. Thus the storm water drainage has to cope with more water than it was designed for. This results in flash-floods, so the councils decide to shift the blame for this from themselves to "people parking their cars on their front gardens".
To make it seem more official, they also bring in a charge of £150 to allow you to pave your front garden, subject to "green" concerns, shown earlier. They really haven't thought it out at all (apart from raising £150 per application) as you can pave your entire back garden and feed that run-off into the storm system, for free. Yet 5 square metres or more at the front and bingo! Why 5 square metres? Because only a Smart car has a footprint smaller. And that £150 also goes for replacing existing hard standing, not just new.
But back to the original post, if you can get your trusses treated for £250, have it done. You may never need it, but it one less worry for years to come.
mrmaggit said:
If you read the literature, you have the choice of EITHER using permeable paving OR constructing a soakaway to take the run-off. You are not forced to use permeable paving, which, as you've both said, will silt up in a couple of years anyway.
Sorry, I should have elaborated - I was writing in the context of large scale residential development. There are, of course, many techniques that can be used as part of a SUDS drainage system, but the EA are getting increasingly unrealistic in their demands and will often ask for both soakaways and permeable paving (amongst other features) on new sites, as a matter of course... We've had them asking for soakways and permeable paving on sites on Lias clay, or where we have a capillary break and clean capping layer overlying heavy contamination.Bunch of bleeding bunny-hugging muppets, some of 'em...
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