Insulating inaccessible rafters/roof

oghran

I'm trying to update the insulation in our 2 story farm house, and am looking for some advice on insulating the roof itself.

The horizontal part in the attic isn't a problem, but we have a sloping roof on either side which appears to have little to no insulation.

The only way to access it is from the attic and looking down either side. In my mind the only way to add more insulation would be to slide kinspan boards down the gap.

Is that the best option? Obviously we could start taking ceilings down and work from below, but I'd rather go for something simpler.

rustynutz

I had a similar situation in my own dormer, although there was already some fiberglass between the rafters I wanted to beef it up, the simplest way I found was screw an insulated board to the existing plasterboard and reskim

Calahonda52

rustynutz wrote: »

I had a similar situation in my own dormer, although there was already some fiberglass between the rafters I wanted to beef it up, the simplest way I found was screw an insulated board to the existing plasterboard and reskim

This is not a good solution.
If I recall correctly you have peddled this solution before here and I have penned why its wrong.
I don't have time now to write it all again.
But it is wrong.

http://www.dpcalc.org/
https://www.nsai.ie/S-R-54-2014-Code-of-Practice.aspx

listermint

Spray foam surely

muffler

listermint wrote: »

Spray foam surely

In a 2 storey farm house??????

rustynutz

Calahonda52 wrote: »

This is not a good solution.
If I recall correctly you have peddled this solution before here and I have penned why its wrong.
I don't have time now to write it all again.
But it is wrong.

http://www.dpcalc.org/
https://www.nsai.ie/S-R-54-2014-Code-of-Practice.aspx

Have you a better solution for the OP? I am not just advising from calculations or theories, I have done what I advised in my own house, three years ago, without any problems. If you can do better, do tell

oghran

rustynutz wrote: »

I had a similar situation in my own dormer, although there was already some fiberglass between the rafters I wanted to beef it up, the simplest way I found was screw an insulated board to the existing plasterboard and reskim

Unfortunately we can't afford to lose any height off the already small hallway where this needs doing.

Spray foam while it may work isn't really high up on my list of things to use in the house when I'm trying to keep things as natural/traditional as possible (within reason).

I think I may end up getting someone in to take the ceilings down, add insulated board, and replaster everything.

listermint

muffler wrote: »

In a 2 storey farm house??????

What does the fact it's a farm house have to do with a bag of potatoe chips ?

Joe1919

oghran wrote: »

I'm trying to update the insulation in our 2 story farm house, and am looking for some advice on insulating the roof itself.

The horizontal part in the attic isn't a problem, but we have a sloping roof on either side which appears to have little to no insulation.

The only way to access it is from the attic and looking down either side. In my mind the only way to add more insulation would be to slide kinspan boards down the gap.

Is that the best option? Obviously we could start taking ceilings down and work from below, but I'd rather go for something simpler.

I have similar type roof but was insulated when roof was re-slated. As far as I know, its important not to fully close in this area due to ventilation requirements. I can see nothing wrong with say using 2inches/50mm of insulation. The only problem I see with sliding the boards as you suggest is that there will be a constriction where the rafters are nailed to the joist, but you could get over this by using two boards side by side to fill the space.

muffler

listermint wrote: »

What does the fact it's a farm house have to do with a bag of potatoe chips ?

Apart from using chips to insulate the roof there is plenty of relevance. The OP stated a farmhouse so it must be assumed that with the sloping ceiling its a considerable age and hence would not have breathable roofing felt if indeed it has felt at all.

So how and why would you consider spray foam to be the best option then?

Right2Write

Older house here as well with similar issue. I used a batten and pushed down some 50mm fibreglass insulation, leaving a small gap between this and slates for ventilation. It was hard to see if it was all placed properly but better than nothing. Taking down the ceilings would give a better result but also a lot messier, so weigh up the benefits.