Insulation

[jeff oakley]

I know we have some very knowledgeable  people on here from a building back ground.

 

Jeanette organised one of these free surveys to see how our home fares insulation wise. I am always sceptical with this sort of thing.

 

We already have cavity walls filled with beads, which has worked fine. The loft has the usual fiberglass and we have had no issues at all. However as we approach retirement and will spend longer indoors at home having low energy bills would be nice.

 

I smell bull when he was saying the moisture in the loft is 25% but it has two huge air vents at either end and in the soffits so he was measuring air basically 

 

They have recommended that we have the loft sprayed with a BASF foam product which is breathable and will insulate the roof. Apparently they install a membrane so that there is an air gap between the foam and the felt which stops any issues.

 

Anyone got any experience of this or of pitfalls. No idea yet how much this will cost and it is easy for them to say we will get a 25% saving on fuel costs with nothing to back it up.

 

Is it a worthwhile investment or just snake oil

 

 

[Mark (smokey mow)]

Don’t do it....

 

Sealing the loft can in itself create other condensation problems unless the void between the existing felt and the foam is well insulated.

 

I don’t know the BASF system specifically but some insurers and mortgage lenders won’t cover certain spray foam insulation’s and for good reasons. I’ve overseen the removal of two roofs because the owners couldn’t get a mortgage with it fitted. because of the difficulties of stripping it out it necessitated removing the entire roof, not just the tiles and felt but replacing the rafters as well. 
 

if you do decide to go for it, get some proper independent advice, do plenty of research and don’t be rushed or sucked in to the marketing.

 

IMO if the loft is already well insulated with a minimum of 270mm mineral wool and the loft hatch is insulated then I’d look elsewhere.  
 

start with windows and doors, ensuring they seal well. Modern double glazing is twice as efficient as that which was being fitted 15years ago.  Things like the reveals are often missed as well and a surprising amount of heat is lost around the edge of the frames. 
 

floors are another area and if suspended timber then easy to insulate between the joists with 100mm PIR insulation. 
 

finally think about the age of the boiler and your hot water storage, 25-30years ago these were only 65% efficient but a modern replacement boiler with an invented cylinder would be close to 95%.

[jeff oakley]

Thanks Mark, I had sort of decided that but wanted to just confirm if I was right to do so.

 

All the other things we have already done, windows, heating system etc in the last year or two so not worried there.

 

I can see why people go for the insulation as the spiel is very good when they are doing the presentation, thanks again