Should I insulate floor during refurb?

soldsold

Would like to get thoughts on the logic of insulating my bog standard 1995 bungalow downstairs floor while extending the house:

Reasons to insulate:

1. Will be changing all floor coverings except one room anyway
2. Only 50mm EPS under finished floor slab
3. New extension height can be set to match higher floor level
4. Saves money on heating
5. I can do the job myself

Reasons to not insulate:

1. Cost
2. Labour
3. Dust/ disruption
4. have to lift door heights, cut doors to size and replace skirting boards
5. Will it make a significant difference and have a reasonable payback?

If I do insulate the floor what is the normal structure - assume PU Boards set in battens?

Is it normal to increase door height to match floor height increase?

Thanks for any advice.

BERmad

50mm insulation is not to bad not worth digging up all the floor it would be a lot of hard work and will not lead to a major increase in your heat retention.

I would advice you to spend the money on dry lining the house as it would have a bigger impact than floor insulation and you should put extra insulation in the attic. All though dry lining your house is still very messy but you dont have to change door heights.

35% of the heat in your house escapes through the walls compared to just 15% through your floors.

You would prob have to change your door heights if you did add insulation or you could cut the doors to fit back onto the frame.

My advice would be not to dig up the floor unless you have the money and the time to spend doing this. I think the best thing for you to to is insulate your walls and attic well. There is a good SEI grant out at the moment for doing this work.

soldsold

Definitely not planning to dig up the floor, I was thinking of laying 50mm PU sheet insulation on top of the floor in between battens and laying the finished floor on top (eg engineered timber). What I am really wondering is if this will give much of a payback, at the moment 15% of heat is escaping through the floor but by the time I have the wall cavities pumped, attic insulated to very high levels and possibly later on external insulation added to the walls I would imagine the floor would become a big heat drain on the house.

Now seems to be the time to decide on whether to add insulation or not, as I mentioned just about all the carpets and tiles are being lifted anyway.

However the toilet, sink, shower and bath etc will have to be raised too...

onq

soldsold wrote: »

Definitely not planning to dig up the floor, I was thinking of laying 50mm PU sheet insulation on top of the floor in between battens and laying the finished floor on top (eg engineered timber). What I am really wondering is if this will give much of a payback, at the moment 15% of heat is escaping through the floor but by the time I have the wall cavities pumped, attic insulated to very high levels and possibly later on external insulation added to the walls I would imagine the floor would become a big heat drain on the house.

Now seems to be the time to decide on whether to add insulation or not, as I mentioned just about all the carpets and tiles are being lifted anyway.

However the toilet, sink, shower and bath etc will have to be raised too...

Probably not the best way to go, as all your existing floor finishes, saddles, doors, stairs and thresholds will be affected and you'll reduce your head height in all the rooms.

Every little thing seems to be a deal-breaker thee days, so you reduce the head height at your peril if its already at the recommended minimum.

ONQ.

soldsold

Thanks for the replies. Will probably leave as is and extend the external insulation down well below DPC at external walls.

onq

soldsold wrote: »

Thanks for the replies. Will probably leave as is and extend the external insulation down well below DPC at external walls.

If you're that keen I think there may be some ultra thing foil insulation products that you could install, but I'm not sure just how well they would work with your other floor finishes, and as another poster has pointed out, your playing with fractions of the 15% lost though the floors.

FWIW

ONQ.