Having lived in a heat stealing flag stone floor cottage for years, I'm determined to do something about our 'new' house, which has flags in two rooms. First I'll remove the ugly 1950s lino stuff that was poured over to about 1/4" and does provide some insulation but looks hideous. Then what?

The plan is to mark for identification, then take up most of the flags with a mini digger, dig down a further X? inches, lay a plastic dpc, lots of insulation / say 4" celotex or similar, bed plastic underfloor heating pipes in cement and somehow... bed the flags back in on top and achieve through more luck than judgement a flat surface. Sounds a bit dubious doesn't it. Your experience welcome!

Any general comments on underfloor heating also welcome.

On Wed, 28 Sep 2005 19:06:07 +0100, peterd
wrote:

| bed the flags back in on top and
| achieve through more luck than judgement a flat surface. Sounds a bit
| dubious doesn't it.

*Real* flags were/are never flat so don't try too hard for perfection

--
Dave Fawthrop dave hyphenologist co uk
The London suicide bombers killed innocent commuters.
Animal rights terrorists and activists kill innocent patients.

Dave Fawthrop wrote:

On Wed, 28 Sep 2005 19:06:07 +0100, peterd
wrote:

| bed the flags back in on top and
| achieve through more luck than judgement a flat surface. Sounds a bit
| dubious doesn't it.

*Real* flags were/are never flat so don't try too hard for perfection

You can cris cross the room with a grid of strings, and lay to that for
levelness.

peterd wrote:

Having lived in a heat stealing flag stone floor cottage for years, I'm
determined to do something about our 'new' house, which has flags in
two rooms. First I'll remove the ugly 1950s lino stuff that was poured
over to about 1/4" and does provide some insulation but looks hideous.
Then what?

The plan is to mark for identification, then take up most of the flags
with a mini digger, dig down a further X? inches, lay a plastic dpc,
lots of insulation / say 4" celotex or similar, bed plastic underfloor
heating pipes in cement and somehow... bed the flags back in on top and
achieve through more luck than judgement a flat surface. Sounds a bit
dubious doesn't it. Your experience welcome!

Any general comments on underfloor heating also welcome.



polystyrene is cheaper than celotex, and you only need about 3" of it
really.

I used simple 4" concrete reinforcing mesh and tie wrapped the UFH pipes
to it. You need a pipe every other mesh for a well insulated room, or
every mesh for poor..run the pipe in a double spiral to equalise
temperatres inflow and outflow IYSWIM. Run no more than 100m of pipe per
run, and never ever try and join it under the floor. Bring it all back
to a balancing manifold. If you supsect that diferential expamnsion may
cause slabs to move, cross teh jon with teh pipe slipp[ied loosely into
electrical conduit, so the stress is averaged out.


Then PRESSURE TEST it and KEERP IT PRESSURISED when screeding.

I used slate and tile cement to finish the job. No reason not to use a
thicker mortar bed.

You may need a small expansion joint round the walls covered with skirting.

Depending on what your flags are made of: A mini digger would very
likely smash your flags or chip the edges off etc. I'd lift them
carefully by hand - with bars, wooden supports etc and move with a
parcel trolley. You could photograph them to get them back same way,
but they never fit the same anyway so you might as well to start from
scratch and expect to lose a bit and make good with new stone or
concrete. They want to be bedded on soft sand without any cement or
mortar and placing tight up together where poss. Wide mortar pointing
looks crap but some will be unavoidable but wait until they have been
down for a bit and have settled. Use a weak mix.
Slightly damp soft sand works like a vey weak mortar under the flags
and sets under the pressure and with the clay content drying out.

cheers

jacob

Come to think - if you are bedding in sand then you could miss out the
concrete altogether - compacted hardcore/ sand/ dpm/ insulation/ soft
sand with heating pipes/ flags.

cheers

Jacob

I am doing exactly the same as you want to do, I have everything except the
flags, the recommened way if doing this with wet underfloor heating is: from
the bottom up hardcore whackered, sand whackered, visqeen, 6"concrete,
2"kingspan/celotex, underfloor heating pipes secured to insulation, now
depending on the thickness of your finished floor covering and head room,
recomended 65mm screed for poss. 25mm flooring e.g. slate, you can go down
to minimum thickness screed of 40mm, but you need to add some form of fibre
strenghening.
hope this helps.
"peterd" wrote in message
news

Having lived in a heat stealing flag stone floor cottage for years, I'm
determined to do something about our 'new' house, which has flags in
two rooms. First I'll remove the ugly 1950s lino stuff that was poured
over to about 1/4" and does provide some insulation but looks hideous.
Then what?

The plan is to mark for identification, then take up most of the flags
with a mini digger, dig down a further X? inches, lay a plastic dpc,
lots of insulation / say 4" celotex or similar, bed plastic underfloor
heating pipes in cement and somehow... bed the flags back in on top and
achieve through more luck than judgement a flat surface. Sounds a bit
dubious doesn't it. Your experience welcome!

Any general comments on underfloor heating also welcome.


--
peterd