LOFT INSULATION AND RENOVATION QUESTIONS !!

[Scotty]

Hi,

 

I’m just about to start renovating the loft in our house in Aveyron, and just wondered if anyone had any advice (from building knowledge or previous experience)

 

It’s a very old house, but the loft and roof seem to be reasonably sound. The roof is composed of tiles nailed onto wooden batons/planks, which lay directly onto the sloping rafters. There seems to be no obvious leaks

 

-         Do I need to add a waterproof layer between the tiles and the rafters (involving a complete roof renovation)?

-         What is the best type of insulation to use (I’ve read a lot about the advantages/disadvantages of rockwool, or the newer foil-type insulation), but wondered what would be best for laying in between the rafters on this type of roof? Also can anyone suggest any good makes?

-         What is the best way of attaching the insulation to a sloping roof – can I staple directly onto the wooden batons/planks between the rafters?

-         What is the easiest, most lightweight material to cover the insulation and ‘finish’ the roof (ie. lightweight plasterboard or tongue & groove etc)? I will be attaching this between the rafters, so the rafters are still showing

-         I’m assuming I don’t need planning permission for this, as long as I don’t declare it as another habitable area when it comes to sale?

 

Any other advice would be much appreciated.

Cheers

Scott

[Nick Trollope]

In order;

No, no no no no non non etc etc....

TBH, I'd avoid the high-tech insulation materials, there is some debate as to their insulation value. 20cm of Rockwool (or a hard foam insulation of 20cm equivalence) is you best bet.

Under no circumstances attach to the bottom of the battens. You must allow at least 5cm of air space between the insulation and the bottom of the tiles. The top and bottom of this airspace must be vented. Easier way is to frame the inside of the A frames and insulate behind the frame. If you havent enough depth, then insulate between the A frames and;

Attach plasterbaord to the new framing or the bottom of the A frames. DOn't worry about weight. If plasterboard brings the roof down, you have a different problem and would be replacing the roof anyway! You could use T&G but it is much more difficult to finish, more expensive an (IMHO) looks a little naff (or 80's or Swedish).

In theory, if you add living space you need to declare it. Whether you do or not is up to you. Whether an on-the-ball Notaire would notice is a different matter. If the conversion takes the area of your house over 170SqM, then you have a different set of problems involving an Architect. To avoid this, don't add any windows or roof lights.

 

 

[HoneySuckleDreams]

What a bizarre coincidence as i've just started fumbling with loft insulation  this very evening and would like to ask a similar question:

I'm using those suspente thingies...short bits if steel you screw/nail into the rafters to make it all level and then attach the slimline rails, which you then screw your plaster board onto.   I've just spent an hour trying to fit one piece of 11 layer insulation.. the thin foil stuff over the top of the suspentes (cutting holes for the things) and nailing it in place.  I have to cut short pieces because the distance from wall plate to 1st beam is 165cm i.e. > 145 which is the width the insulation comes in... so I have to fit it vertically not horizantally... I know what i'm talking about anyway!

On that time scale it will take me about 8 days to just fix the insulation...even if I get myself together a bit more.

Anyway... simple question... can I fit the insulation directly onto the horizantal rails for the ceiling (fit all the rails first), i.e. no gap between the isolante and the plaster board? Will i get condensation? I've got plenty of gap behind the isolante and tiles. I would like to do it right the 1st time.

thanks

p.s.I apologise if someone has discussed this before, but i've tried using the search box on the forum but keep getting an error message thus : Server Error in '/cs' Application ... any webmeisters out there who can help? as my pet geek is on holiday 

[Nick Trollope]

Yes you can, and you will get no ill-effects - other than the performance of the insulation will be reduced even further. You are supposed to have a gap of at least 25mm either side of these insulation types, I believe.

Again, I don't believe these things work particularly well - I have tried both (high-tech and glassfibre) in virtually identical situations - the old method works so much better.

Another example; I was working in a loft today (not paticularly sunny around here), which has had foil insulation applied to the roof. It was over 30 degrees in the attic - this "insulation" was certainly not working one way, at least.

 

[Scotty]

Hi Nick and crazyfrog!

Cheers for your replies - its all really useful and will hopefully make my life much easier!

Sounds like I'm gonna go for the rockwool or equivalent, and obviously leave enough space either side for ventilation

I'm interested to hear any more info you have about these Suspente metal rails? Is that easier to use than wood (I was just going to build a frame using thin wooden batons to attach the insulation and plasterboard to.. If so, where can I buy it? Is it pretty easy to work out what you need?

One other question, which might sound a bit silly. Is there an easy way to attach rockwool between the rafters, bearing in mind its not a solid material? Is it best just to build a frame between the A-frame rafters and nail it to this?

cheers all

Scott

[HoneySuckleDreams]

Scotty

The suspentes are only useful if you want to build a flat, straight ceiling away from the rafters.  I think you want to attach the plasterboard between the rafters? battens will be fine for this.  I'm using the suspentes to make sure the new ceiling projects beyond the line of the rafters as it would have been too much effort in cutting each piece of plasterboard to fit (rafters are all different thicknesses... have a look at the width at the bottom and the top...if it's a new roof you might be OK, but old properties don't make it easy to infill between). Plus I want to put some downlighters in, and I would not have enough space between the tiles and the plasterboard if i just screwed the plaster board into the rafters.  Once you have put your battens up the rockwool should stay in place...or put a batten across at various points to keep it in.

Have fun