Under-floor Insulation.

[securespark]

Thinking about putting Celotex or similar under my bedroom/en-suite floor. The room is over an unheated garage.

In the bedroom there is only one rad to worry about, so that's not a problem.

But I'm thinking about all the water and waste pipes and the shower trap in the en-suite.

This trap is the Mira rectangular type.

Although it is impossible to insulate the room completely from below (ie under the garage ceiling), it is possible to insulate just the en-suite from underneath.

Is this a viable proposition?

Cheers folks.

 

[KenGMac]

securespark, good evening.

Short answer is yes I believe it is a runner.

Do you have complete access to the under floor area? that is, no ceiling material??

If it were me, I would for rigid insulation in some form, and cut and patch the insulation around and more especially over any, shall I call them "obstacles" ??

Ken.

 

[securespark]

Thanks, Ken.

Sadly, the garage ceiling is intact.

I will have complete access to the floor void from above.

The thing that bothers me is that I would have to remove insulation where the shower trap is going. I'm trying to completely (or as completely as I can) isolate the cold space below from the warm above.

Hence the idea to insulate all of the bedroom from above and ally tape over the joists, then insulate the en-suite (which is formed from a corner of the bedroom) from underneath, fixing the Celotex to timber battens, making sure to overlap from below the insulated area in between the joists above.

This the leaves the floor void under the en-suite free of insulation and less hassle for plumbing.

 

[foxhole]

I insulated a ceiling from above , Removed a couple of floor boards then loose lay insulation pushed out from centre to edges using a push stick I made for the job (like a broom without bristles).

 

[KenGMac]

OK, an off the wall [or ceiling] Consideration

How about use [say] 50 X 50 bearers and then fix Inert insulation board, between the bearers then over board with Fireline??? Plasterboard.

You will probably need to re-jig the electrics to the lights Etc?

Just trying to think around the issue??

With the above, you can insulate the lot in one hit? may cost a wee bit more but good to be warmer??

Ken

 

[securespark]

This spectacularly rubbish drawing gives an idea of what I propose.

My only stumbling block is what to do if the en-suite does not finish on a joist....

 

[securespark]

OK, an off the wall [or ceiling] Consideration

Nice!!

With the above, you can insulate the lot in one hit? may cost a wee bit more but good to be warmer??

If I understand you correctly, I can't insulate the whole floor area from below as there are pipe runs front to back on the garage ceiling for the combi, which are spaced off the ceiling.

There just isn't the headroom.

But I am able to insulate the en-suite floor from below.

But as I say, I'm unsure how to proceed where the en-suite floor area (insulated from below) borders the bedroom floor area (insulated from above).

 

[KenGMac]

Right, hope this works??

The timber beam between the two rooms is a reasonable insulator, if you "add" some further insulation as indicated Red [or nearly Red] in this position it should reinforce the overall insulation in place.

Sorry but I copied and used Win Paint to try this out, I do not like Paint.

Ken

 

[securespark]

Thanks, Ken, appreciated.

And if that drywall returned across the joists (rather than along the joists, like the one in the diagram) to complete the partitioning of the en-suite off from the bedroom, how would you finish off the insulation "box" underneath?

 

[Swwils]

What's going on with the insulation above, and the wall of the room?

Just want to make sure the most effective place to work is below the room!

 

[JohnD]

most of the heat loss through a floor is by draughts. Obviously there is no convection loss. If you stuff the cavities between the joists at each end with mineral wool, there will be little air movement, this is where the draughts usually start, and they like to come up through the gap under the skirting, so give that extra attention. any gaps and holes I fill with fire foam.

I did a floor above my garage when the old chipboard came up. From above, I could foam round any loose-looking bits, e.g. where the ceiling plasterboard met the walls, and some pipes, but mostly the wool was fine.

edit
oh, I see it's an old thread. thought it seemed familiar.