Advice on attic insulation options

[Leo]

We have no downlights so just have to ensure the wires for the alarm etc are laid on top.

Wiring for alarms is low voltage & low power, you do not need to worry about it overheating under insulation.

Removing the old insulation is probably the thing I find most daunting given the toxic nature of fibreglass.
Just curious if others think it can just be bagged into a set of black plastic bags? Would double bagging be best?

A combined mask/ eye protection like this would make the job a little less unpleasant. Fibreglass is an irritant, it's not toxic and so single bagging is sufficient. Any of the pieces in good condition can just be laid back out on top of the new insulation, won't add a lot of benefit in terms of insulation value but will save you having to dispose of bulky material.

 

[horse7]

If you decide to use foam insulation on the roof rafters while giving you floor space are there any problems with someone getting a mortgage from a bank to buy your property?

 

[mir2001]

Just thought I'd finally update this, after much messing about, I got some parts of the attic done but I found it difficult to get the large insulation roll opened out right beside the eaves. So eventually I gave up and asked a guy I know who has a good bit of DIY experience to finish it. He removed the old flooring and put down 200mm underneath and then added new flooring, raised up by adding extra timber. I could probably do the insulation part entirely myself having now watched somebody else do it, not sure I could ever properly do the flooring. If I was to do it again I would look to use @Jazz01's suggestion to use rigid insulation in the floorboard area. And I would start it in spring/summer so I wasn't working in freezing cold conditions

 

[ClubMan]

Just thought I'd finally update this, after much messing about, I got some parts of the attic done but I found it difficult to get the large insulation roll opened out right beside the eaves.

Hopefully you/he didn't roll it out right to the eaves and block ventilation into the attic?

 

[Zenith63]

If I was to do it again I would look to use @Jazz01's suggestion to use rigid insulation in the floorboard area. And I would start it in spring/summer so I wasn't working in freezing cold conditions

FWIW I think you went the right way. I’ve spent hours of the summer working in my attic and it is absolute hell up there with the heat, I would take a bit of cold over the stifling heat any day!

As for the rigid insulation, we have that in our house and I’d be very cautious of using it again. It needs to fit tightly to the plasterboard underneath, otherwise cold air will blow under it and the insulation may as well not be there. Joists are not 100% parallel or vertical and tend to be crisscrossed with cables, pipes and lights, making retrofitting rigid boards properly nearly impossible. Then the first tradesperson up there who needs to move the insulation will pull it away from the plasterboard, not refit it properly and insulation will drop to 0.

 

[mir2001]

Hopefully you/he didn't roll it out right to the eaves and block ventilation into the attic?

Hopefully not, I found that hard to judge, initially I left too big a gap in some places. I'm sort of keeping my fingers crossed that the rest of it was laid out correctly.

 

[Pinoy adventure]

. And I would start it in spring/summer so I wasn't working in freezing cold conditions

Having spent the day yesterday up in two un insulated attics I can confirm it’s much better too work in them during winter months rather than warm summer months.

 

[lff12]

When I got it done, the company who came and did it topped up to 300mm, put in a new door and added insulation strips around it and catches to close it securely, they also added a meter squared of flooring around the water tank, insulated the tank and all pipework. They properly segregate wiring and light fittings. I have a velux shaft that runs from the stairwell to the roof (classic Bovale feature). that was entirely uninsulated and they wrapped it in rock wool. It probably raised the internal temperature by around 3c.
It was worth getting it done professionally. I think I paid out around 2k and got 1.3k back on the grant. I didn't bother with flooring as I have a lot of other work to do on the house.
Not sure what to say to you about the old insulation - that's why I got professionals to come and do the lot.

 

[mir2001]

When I got it done, the company who came and did it topped up to 300mm, put in a new door and added insulation strips around it and catches to close it securely, they also added a meter squared of flooring around the water tank, insulated the tank and all pipework. They properly segregate wiring and light fittings. I have a velux shaft that runs from the stairwell to the roof (classic Bovale feature). that was entirely uninsulated and they wrapped it in rock wool. It probably raised the internal temperature by around 3c.
It was worth getting it done professionally. I think I paid out around 2k and got 1.3k back on the grant. I didn't bother with flooring as I have a lot of other work to do on the house.
Not sure what to say to you about the old insulation - that's why I got professionals to come and do the lot.

That’s very interesting feedback, thanks for posting. I paid more than that between the cost of materials and paying the guy who helped for his time. I suspected afterwards that this might be the case. And our attic door is still uninsulated so there’s that too. We definitely didn’t notice a perceptible increase in temperature either. Was expecting the technical assessor to say it wasn’t quite right but he thought it was fine. But I guess maybe they don’t assess it in depth.

 

[lff12]

That’s very interesting feedback, thanks for posting. I paid more than that between the cost of materials and paying the guy who helped for his time. I suspected afterwards that this might be the case. And our attic door is still uninsulated so there’s that too. We definitely didn’t notice a perceptible increase in temperature either. Was expecting the technical assessor to say it wasn’t quite right but he thought it was fine. But I guess maybe they don’t assess it in depth.

They should visually check to see that it is 300mm and that it covers the entire surface. They also look at what material was used.

 

[mir2001]

They should visually check to see that it is 300mm and that it covers the entire surface. They also look at what material was used.

He did note the depth but I wondered if he checked that it was uniformly that depth. He also didn't seem to think it mattered that much that the depth was only 200mm under the floored area.