Insulation Options to reduce thickness

[LeeWoods]

This is my first post...take it easy on me.

We are about 30% into our build and up to ground floor level above basement. There has been discussion between Architect, Builder and Structural Engineer over the concrete beams that have been used which are 220mm as opposed to 150mm initially specified. We are spanning 4.9 metres which is over the upper limits of 150mm beams. The manufacturer, rightly so it seems, upped the thickness. Therefore we're about 75mm lower in our ceilings. What options do we have outside of traditional 100mm insulation to compensate for that height loss...out builder mentioned some alternative insulations which are very expensive. Does anyone have any insights as to what those products might be and/or other alternatives to 100mm insulation.

 

[motorbiking]

The beams can be clad with conventional insulation or boards. I'm assuming its an "I" beam? It depends on the external finish to some degree as you may not be able to clad both sides. It shouldn't cost a lot though.

I cut celotex to fit my I beams which from memory where slightly bigger than yours. I oversized the panels a few mm, which mean the could would hold tight when tapped into position. I'm not convinced it makes a huge difference however, as metal conducts very differently, but it was a low cost better than nothing option.

You are supposed to clad the whole beam to address this, but I didn't bother as it wasn't practical.

I'd check that services aren't impacted in the design change as things like bathroom/toilet waste pipes can become complex .

If the beams are bridging an external wall which is to become internal as a result, then I wouldn't bother insulating at all

 

[geraldthehamster]

I think the OP is referring to a concrete beam and block floor...

 

[freddiemercurystwin]

The OP's first post is not clear, is this the floor between the basement and ground floor or what? Is this the insulation going at the basement floor level and the beams are at ground level? Some clarity please OP .......

 

[motorbiking]

sorry - he does say concrete beams and not I beams... I'll get my coat.

 

[endecotp]

we're about 75mm lower in our ceilings.

In the basement or the ground floor? I.e. has the extra beam thickness been taken from the basement ceiling or the ground floor floor?

out builder mentioned some alternative insulations which are very expensive. Does anyone have any insights as to what those products might be.

Probably spacetherm / aerogel, or maybe vacuum insulation panels. Google can find details. Both are very expensive, and probably not a realistic option.