It pains me to say this, but I may have made a minor cock-up.
The sort of thing that for some reason just did not occur to you at
the time ;-(
When I layed the main concrete floor slab, I had insulation under and
around the edge, as you do. The perimeter insulation was cut off level
with the concrete slab.
When I layed the screed (between 40mm and 70mm), I kind of "forgot"
about perimeter insulation and screeded right up to the edge, sort of
thinking about a good solid floor to the edges, and fogetting that
25mm insulation would be covered by plasterboard / skirting etc.

So I have a 5 inch concrete slab with underneath and perimeter
insulation, covered with up to 3" screed touching the inner leaf below
DPC (against the lapped DPM).

Now, obviously you cannot have perimeter insulation across the
doorway, but there is around 15 metres of other wall.

Question: Is it worth cutting out a 25mm channel and adding permeter
insulation, or is it not worth it now ?
Floor will be tiled and no underfloor heating.

Simon.

On 19 Oct, 09:02, sm_jamieson wrote:
It pains me to say this, but I may have made a minor cock-up.
The sort of thing that for some reason just did not occur to you at
the time ;-(
When I layed the main concrete floor slab, I had insulation under and
around the edge, as you do. The perimeter insulation was cut off level
with the concrete slab.
When I layed the screed (between 40mm and 70mm), I kind of *"forgot"
about perimeter insulation and screeded right up to the edge, sort of
thinking about a good solid floor to the edges, and fogetting that
25mm insulation would be covered by plasterboard / skirting etc.

So I have a 5 inch concrete slab with underneath and perimeter
insulation, covered with up to 3" screed touching the inner leaf below
DPC (against the lapped DPM).

Now, obviously you cannot have perimeter insulation across the
doorway, but there is around 15 metres of other wall.

Question: Is it *worth cutting out a 25mm channel and adding permeter
insulation, or is it not worth it now ?
Floor will be tiled and no underfloor heating.

Simon.

Seems a lot of work to me especially if your inner leaf is insulation
block and you have cavity wall insulation.

On 19/10/10 09:02, sm_jamieson wrote:
It pains me to say this, but I may have made a minor cock-up.
The sort of thing that for some reason just did not occur to you at
the time ;-(
When I layed the main concrete floor slab, I had insulation under and
around the edge, as you do. The perimeter insulation was cut off level
with the concrete slab.
When I layed the screed (between 40mm and 70mm), I kind of "forgot"
about perimeter insulation and screeded right up to the edge, sort of
thinking about a good solid floor to the edges, and fogetting that
25mm insulation would be covered by plasterboard / skirting etc.

So I have a 5 inch concrete slab with underneath and perimeter
insulation, covered with up to 3" screed touching the inner leaf below
DPC (against the lapped DPM).

Now, obviously you cannot have perimeter insulation across the
doorway, but there is around 15 metres of other wall.

Question: Is it worth cutting out a 25mm channel and adding permeter
insulation, or is it not worth it now ?
Floor will be tiled and no underfloor heating.

Simon.

Without UFH I wouldn't bother. If you have insulation under the concrete
I would think your edge losses though 3" with say a 15C surface temp
will be next to bugger all, though that is more of an instinctive
feeling rather than with real maths. Screed is not a thermal
superconductor so the worse case is that the floor edge might run a
little cooler than the middle - but I don't think it will be leeching
100's Watts out of your room.

Cheers

Tim

On 19 Oct, 09:31, Tim Watts wrote:
On 19/10/10 09:02, sm_jamieson wrote:



It pains me to say this, but I may have made a minor cock-up.
The sort of thing that for some reason just did not occur to you at
the time ;-(
When I layed the main concrete floor slab, I had insulation under and
around the edge, as you do. The perimeter insulation was cut off level
with the concrete slab.
When I layed the screed (between 40mm and 70mm), I kind of *"forgot"
about perimeter insulation and screeded right up to the edge, sort of
thinking about a good solid floor to the edges, and fogetting that
25mm insulation would be covered by plasterboard / skirting etc.

So I have a 5 inch concrete slab with underneath and perimeter
insulation, covered with up to 3" screed touching the inner leaf below
DPC (against the lapped DPM).

Now, obviously you cannot have perimeter insulation across the
doorway, but there is around 15 metres of other wall.

Question: Is it *worth cutting out a 25mm channel and adding permeter
insulation, or is it not worth it now ?
Floor will be tiled and no underfloor heating.

Simon.

Without UFH I wouldn't bother. If you have insulation under the concrete
I would think your edge losses though 3" with say a 15C surface temp
will be next to bugger all, though that is more of an instinctive
feeling rather than with real maths. Screed is not *a thermal
superconductor so the worse case is that the floor edge might run a
little cooler than the middle - but I don't think it will be leeching
100's Watts out of your room.

Cheers

Tim

Thanks, its probably not a big deal.
And wife would hate another dusty job ;-)
Simon.

sm_jamieson wrote:

Question: Is it Â*worth cutting out a 25mm channel and adding permeter
insulation, or is it not worth it now ?
Floor will be tiled and no underfloor heating.

Question 2: Isn't one of the functions of the perimeter insulation to allow
for the relative expansion of the underfloor concrete slab?

AJH

On 19 Oct, 19:20, andrew wrote:
sm_jamieson wrote:
Question: Is it *worth cutting out a 25mm channel and adding permeter
insulation, or is it not worth it now ?
Floor will be tiled and no underfloor heating.

Question 2: Isn't one of the functions of the perimeter insulation to allow
for the relative expansion of the underfloor concrete slab?

AJH

Yes, and is vital with underfloor heating, but there are loads of
solid floors out there before they ever used perimeter insulation, so
it must be OK for an unheated floor which undergoes far less
temperature changes.
I've actually got some air gap there anyway, since in some areas the
vertical part of the DPM was slightly saggy and I didn't jam the
screed up that hard against the side.
Simon.