Insulating a cold room in a new house

tagoona

Looking for a bit of advice re: insulating a room.
Basics: House built about 2 years ago by developer who has since gone tits up.
Room was previously only used for storage and guests, but expanding families have put paid to that.
Room is built into a roof space, so mostly shaped like an upside down V with sides truncated by plasterboard(to make things liveable , presumably).

I was recently installing a wardrobe and decided to cut through the plasterboard and investigate why the room is always cooler.
The insulation in between the joist is only what is attached to the picture. There looks to be plenty of room for more insulation in the roof space.

So my questions are:
1. Is the insulation already there adequate?
2. Is there an easy way to put the insulation in? i.e., do I
A. Push another insulated board all the way along the cavity or
B. Take down all the plasterboard on the roof and do it again.
3. What type of insulation would I be able to put up there.

brendankelly

We used that insulation a few years ago. it is easy to work with and cut. I do not know what the rating for it is but in your case it is well installed. You need the gap between the insulation and the felt for ventilation. I suggest you leave it as is, counter baton, put in either sheep's wool or hemp mats and slab it with a breathable board.

tagoona

cheers for that.

MicktheMan

From the photo, I see two problems with the insulation installation.
1. The piece on the right is not tight against the plaster board, looks like 8-10mm gap. This severly reduced the effectiveness of the insulation as cold air can get between the insulation and the plasterboard.
2. The insulation boards (rafterloc) is cut too narrow and is therefore not compressed enough. You shouldn't be able to see any gaps between the slits. Again good insulation thrown in any aul way.

If the rest of the roof is thus insulated, imo this is one of the reasons why your room is cold. Insulation installation is not difficult when you know what you're doing and why you're doing it. The best insulation will perform poorly if not installed correctly.

tagoona

Thanks for that micktheman.
So I'm presuming the recommendation would be to compress the rafterloc with more rafterloc, and leave the ventilation gap to the felt.
I would also need to insert some sort of spacer to ensure the rafterloc presses tight against the plasterboard?

cardwizzard

Depends on your budget of course. You could always take it down and start again and maybe spray the insulation in. I think it gets in to all the angles and corners and is very effective. I've seen this done a lot in the U.S and it's the biz. There is companies here that do it, by the way i'm not in anyway attached or even know them. Of course it may be expensive but it could sort out your problem for life.

MicktheMan

tagoona wrote: »

Thanks for that micktheman.
So I'm presuming the recommendation would be to compress the rafterloc with more rafterloc, and leave the ventilation gap to the felt.
I would also need to insert some sort of spacer to ensure the rafterloc presses tight against the plasterboard?

Basically, what you need to do is ensure there are no gaps from the cold side to the warm side. Once the rafterloc is in place it shouldn't move so there wouldn't need to be a spacer used, just attention to detail.

MicktheMan

cardwizzard wrote: »

Depends on your budget of course. You could always take it down and start again and maybe spray the insulation in. I think it gets in to all the angles and corners and is very effective. I've seen this done a lot in the U.S and it's the biz. There is companies here that do it, by the way i'm not in anyway attached or even know them. Of course it may be expensive but it could sort out your problem for life.

A big concern I would have with spray foam insulation is moisture buildup in the roof timbers leading to rot and failure of the roof within a very short time. :mad:

cardwizzard

Mick, so how do these companies do it. I'd say they must have a system that works otherwise they will be out of business in a flash. As I said i've no idea, just enquiring.

heinbloed

I'd say they must have a system that works otherwise they will be out of business in a flash.

They come and go in Ireland.

Get the moisture risk analysed using a software which can figure out the Dynamic Moisture Risk. Changing temperatures, changing moisture content, different forms of aplication.
Wufi ( the name of a software) might be helpfull.

Macspower

Just to clear up a few misconceptions on the spray foam.

There are many products out there and there are many installers... there are only 2 companies using NSAI certified foam. The one I'm familiar with is certified 96% breathable and suitable for the purpose which it is intended for...

Non certified products are just that... non certified!

I work for a spray foam company and know the business very well. Unfortunatley like many other businesses there are many cowboys out there!

While I have a vested interest in spray foam insulation I will gladly answer any questions anyone has on products honestly with no bull..

paddy147

Macspower wrote: »

Just to clear up a few misconceptions on the spray foam.

There are many products out there and there are many installers... there are only 2 companies using NSAI certified foam. The one I'm familiar with is certified 96% breathable and suitable for the purpose which it is intended for...

Non certified products are just that... non certified!

I work for a spray foam company and know the business very well. Unfortunatley like many other businesses there are many cowboys out there!

While I have a vested interest in spray foam insulation I will gladly answer any questions anyone has on products honestly with no bull..

Can you PM me the name of the 2 certified companies please?

And what the best type of foam for spraying an existing attic in a semi detached house?

Would the spray foam cause any problems with the wooden roof joists and the roof underlay/membrane down the line??

Thanks.:)

soldsold

Would appreciate a pm on this too, I'm not convinced about the safety of spray foam re. roof timbers rotting but the inlaws have a job to do on an old roof that just has space for spray foam but no other options, the roof doesn't have long to go anyway and the foam is to stop pipes freezing next winter

Macspower

paddy147 wrote: »

Can you PM me the name of the 2 certified companies please?

And what the best type of foam for spraying an existing attic in a semi detached house?

Would the spray foam cause any problems with the wooden roof joists and the roof underlay/membrane down the line??

Thanks.:)

certainly.. one is in my sig pm sent with the other

As regards your own house I would recommend only breathable and certified foam. We use BIO Foam 800 which has the Irish Agrement certificate and is certified 96% breathable. It must allow your rafters to breathe.

I would also recommend the use of a vent card. this card makes a 25mm gap between the foam and the felt. the foam can be successfully sprayed directly to the felt but I recommend the vent card as it stops pockets of moisture forming between the outside of the felt and the slate if the foam has pushed the felt into a bubble creating valleys...

I can only speak for our own product. It will not cause any problems with your rafters or felt at any stage.. your concerns are not unfounded as there are many foams out there that were used in the past that were not fit for the purpose which they were used. It all comes back to the NSAI Irish Agrement Cert. If the foam used has this you are safe.. if it doesn't then ask yourself why..

Macspower

soldsold wrote: »

Would appreciate a pm on this too, I'm not convinced about the safety of spray foam re. roof timbers rotting but the inlaws have a job to do on an old roof that just has space for spray foam but no other options, the roof doesn't have long to go anyway and the foam is to stop pipes freezing next winter

PM sent...

I hope the NSAI Agrement Cert might ease your mind a little regarding the spray foam..

Regarding your inlaws roof I'm asuming as it's an old roof that it might not have any felt or the felt is damaged? If so we spray a thin layer of closed cell semi breathable foam first to seal the slate and then we spray our 96% open cell foam. There is no reason that their roof cant last for years unless there rafters are in very poor condition..

It will definately stop their pipes and tanks freezing..

brendankelly

This was debated on another forum and from what I can gather there are 2 types of spray foam. One is oil based and the other is water based. One is breathable and the other is not> I am not an expert on this but can guess which one is breathable. So be careful.

Ps If you need to go to the toilet the NSAI cert is useful.