Retrofitting UFH

[Onoff]

Years back when we first got the place I, for want of a better word "lined" the old single skin boot room / scullery. There was a step down from the main house level. Having no real idea of what I was doing I made probably every mistake going. That being said it's the warmest room in the house!

 

First I Kangoed the rough floor then just reconcreted it over a DPM.  There's no insulation under the slab!

 

I then built a Celcon wall inner skin with a 60mm gap and 50mm Rockwool batts. Tied with frame fixings to the outside wall. Then I battened this new skin and put in another 50mm of Rockwool batts and plasterboarded over the top. The insulation doesn't go all the way down to the slab. I know, a lot of work when there was no doubt a better way!

 

To bring the floor up level with the rest of the house I made a frame of 4x2, literally like a stud wall carried it in and laid it on the concrete floor on waxed building paper. I made it slightly smaller all round by about 6" so I could get it in. It's levelled on 100mm squares of ply from 6 to 18mm thick to account for the rough concrete. Wherever they fitted tight I just lifted the frame and glued them. Between the joists I laid just 100mm of roll insulation. All topped off with 22mm T&G chipboard flooring and carpeted.

 

With hindsight eh!

 

Half thinking to take a Skill saw to the floor and cut out a big rectangle. Then drop in 75mm of tight fitting PIR between the joists in place of the roll stuff.  Should leave me a nom 25mm gap between top of PIR and tge underside of the T&G chip.

 

Within that 25mm gap I'd run a (serpentine?) loop of Pex-Al-Pex drilling holes in the joist as necessary.

 

A bit of an issue is the gap around the edges. I left it as much as anything for ventilation and "air flow". I think though that is in effect a "cold" perimeter. I was worried about vermin using this perimeter "void" as a "rat run". I think I gun foamed some 110mm pipe offcuts in there stuffed with balled up chicken wire.

 

I wouldn't be cutting the floor out either right to the edge as I've fitted book shelves along one long wall and a slide door, full width, walk in cupboard on one of the short sides. 

 

Worth doing or will it be too "lossy"?

 

 

 

Edited December 6, 2017 by Onoff

[Dudda]

I think you’d be mad to go messing with it. Aren’t you thinking external insulation long term? I presume that will cover this room you’re on about so I’d wait until that’s done and then see what’s required heat wise.

Would you not finish the bathroom first?

[Onoff]

6 minutes ago, Dudda said:

I think you’d be mad to go messing with it. Aren’t you thinking external insulation long term? I presume that will cover this room you’re on about so I’d wait until that’s done and then see what’s required heat wise.

Would you not finish the bathroom first?

 

Long, long term EWI yes.

 

Just fancy the luxury/comfort element of UFH. Lots of hours sat in this room gaming, homework etc. It's right next to the stairs room where the manifold will go anyway. Doesn't seem a lot of work to do tbh. 

 

And to think MY plan for this room was BFO telly/sofa/beer fridge. Htf did it end up with a bookcase full of cookery books she'll never open and Barney videos they'll never again watch? Not to mention the cupboard full of SCART leads and dead electrical things!

 

"...finish the bathroom first?"

[Ferdinand]

Ignore the humbug about bathrooms.

 

Do just enough to make this unusable then you will have extra motivation for the bathroom.

 

 

 

Edited December 6, 2017 by Ferdinand

[Onoff]

7 minutes ago, Ferdinand said:

Ignore the humbug about bathrooms.

 

Do just enough to make this unusable then you will have extra motivation for the bathroom.

 

 

 

I've already got 4 16mm pipes that snake across the stairs room in the rough direction of where the manifold will be. A semi permanent fixture, my kids have learnt to avoid them even in the dark but they still catch the unwary out! Another couple of pipes won't hurt.

[Nickfromwales]

Go for it as you'll have ( when I get around to posting it  ) a big enough manifold anyhoo. 

Then one thing you MUST use is aluminium spreader plates. I'd leave the rockwool in TBH as I don't think you'll really notice the difference in the real world. 

Decking up...

Spreader plates down...

Pipe in...

Deck back down...

Drink beer. ?

If you switch the OCD off ( easier said than done ) you can do this on a weekend start to finish. Set yourself a target to be done and just do it.