Insulation

[Cassie]

Hi folks, just a quick one. I’ve just read the chapter on insulation in Pete Ward’s new book. Eek. Def need to get up in the loft and try to fathom out the scale of the problem (insulated between rafters with rock wool, unsure of how far it goes down etc) Anyway, that’s not the question, at least not today! The sash window shutter boxes in the lounge are open at the back to the brick. A howling gale was coming through them and to try and warm things up a bit until I get round to making new shutters, I stuffed them with some fibreglass insulation. Not very well I must add, there’s still a bit of a draught, but not enough to turn the page of your book The floorboards go into the shutter boxes underneath, but don’t meet the brick wall. The joists span across the bay. Have I made a bit of an error here? Is this the ventilation for the suspended floor that I’ve stuffed up? There are plenty of gaps in the floorboards and under the skirting to facilitate ventilation (although I’ve been thinking about pushing in some sort of foam strip to reduce that) and the floor is partially covered with a wool rug rather than fitted carpet. Mr ward seems very against fibreglass (and some of his photos are very convincing!) Would replacing with wool be better?? Cheers all!

 

[Roger440]

Hi folks, just a quick one. I’ve just read the chapter on insulation in Pete Ward’s new book. Eek. Def need to get up in the loft and try to fathom out the scale of the problem (insulated between rafters with rock wool, unsure of how far it goes down etc) Anyway, that’s not the question, at least not today! The sash window shutter boxes in the lounge are open at the back to the brick. A howling gale was coming through them and to try and warm things up a bit until I get round to making new shutters, I stuffed them with some fibreglass insulation. Not very well I must add, there’s still a bit of a draught, but not enough to turn the page of your book The floorboards go into the shutter boxes underneath, but don’t meet the brick wall. The joists span across the bay. Have I made a bit of an error here? Is this the ventilation for the suspended floor that I’ve stuffed up? There are plenty of gaps in the floorboards and under the skirting to facilitate ventilation (although I’ve been thinking about pushing in some sort of foam strip to reduce that) and the floor is partially covered with a wool rug rather than fitted carpet. Mr ward seems very against fibreglass (and some of his photos are very convincing!) Would replacing with wool be better?? Cheers all!

I know he is.

However, ive never had a problem with it where its installed correctly, ie still good airflow.

If you have damp in your roof, i think id try to fix it first.

 

[Cassie]

Thanks Roger-not anywhere near the roof yet, although rising energy bills are making me think I should Trying to concentrate on fixing the wet porch, but various obstacles have arisen (you’re probably not remotely interested, but it’s been a bit of a saga one way and another-I’ve asked a lot of questions here!) Roof insulation next because I *hope* I can tackle that myself. I can’t afford the bathroom reno I need because of the lead I need on the porch Anyway, question wasn’t about the roof, more about the sash shutter boxes- to insulate or not? Fibreglass or wool?? I think it will fall into Malcolm’s small jobs category

 

[fernicarry]

Ventilation for your suspended floor, if its ground floor level that is, should be crosswise via air bricks in the outside wall. If its upstairs I don't think you particularly need to worry about ventilating between floor and the ceiling below.

Ideally you want to discourage this ventilation from coming into the habitable spaces -- gaps between floorboards, under skirtings, around electrical accessories, window cases etc. Bit of a job of whack-a-mole.

Personally I think its fine to make window reveals as air tight as possible and I certainly stuff as much insulation in there as I can whenever I have access. I'm also experimenting with putting a breather membrane under the floor boards and lapping that up behind the skirting boards. You need to be able to get under the floor or lift the boards to do that.

If you have a draft around the window then you might find that the mastic on the outside of the window between the frame and the masonry has failed. I had that redone before last winter along with the pointing and it made a big difference to the comfort levels.

Failed mastic also allows water penetration, particularly bad here as we are exposed to the sea. One of my window openings was pretty apocalyptic, joist ends gone, floor boards gone, wooden paneling held together with nothing but paint.... all due to water getting in around the window frame.

I've chucked away all the fibreglass here. Only use the thermafleece stuff now, but the cost is quite eye watering.

 

[Lacan07]

Rock wool is apparently breathable but expensive compared to standard fibreglass, how it reacts to getting wet however might be a problem. Others here might be able to shed further light? On the plus side its easily sourced.

Other than you're looking at sheep's wool or flexible wood fibre (steicoflex)

 

[a twig]

Had no issues with proper rockwool in our cellar ceiling and it’s a lot cheaper than sheep’s wool!

Also had a lot of success with Thermafleece’s Supasoft which is made from recycled plastic.

 

[Cassie]

Thanks all
Fernicarry-it’s not the window that’s draughty, it’s the shutter boxes below the window. The windows are unfortunately nasty plastic but appear to be fairly well installed and serviceable, but remain on my wish list for future replacement! The shutter boxes don’t have a timber backing, they are just open to the internal side of the exterior wall. Surprisingly bone dry, presumably due to the excellent ventilation ie. Howling draught from what you’ve said, the floor ventilation doesn’t seem to be an issue, it’s on the first floor. But will I get condensation/damp issues around the shutter boxes/remains of the window frame by reducing ventilation?
I have done a quick and dirty job of decorating this room to give us one habitable, non-building site space to sit in, but there’s quite a bit of bounce on the floor so once many other things are done, I’ll revisit this room and have the floorboards up to check on the joists etc. At that point, I guess I’ll be thinking about insulating/reducing draught everywhere in the room. That’s a long way off though!
So in conclusion, there’s still ventilation, but less than before: I’ll keep an eye on it and if I see signs of damp/condensation, I’ll have a rethink. Sound like a plan?!

 

[Cubist]

My understanding is that under-floor ventilation is much less important for upper floors. Its really about helping damp rising from the earth and groundworks to dissipate through the atmosphere. In your place I would get as much insulation as seems sensible in there and keep an eye on things just to be sure.

 

[Cassie]

Cheers cubist. Fortunately there’s a fire in that room, so despite the massive windows, north facing aspect and draught, it’s nice and cosy when the fire is lit. I’ll stuff a bit more insulation in as material becomes available!