Floor screed - My House Extension

A one storey extension
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Floor screeding
Tuesday, 12th June: I haven't really done anything today due to other commitments but I've started getting things together for the 60mm screed. The slab will be covered with 80mm of insulation and 60mm of screed.

The insulation selected is 90mm Celotex. I had a sheet left over from the roof so I have ordered two more sheets which should be enough to complete the floor.
I've bought some in-screed channelling that I will use to feed around two 15mm copper central heating pipes to two radiators.

As they are 50mm deep, I will place 10mm wood spacers below them to bring the tops of the channelling flush with the surface of the screed.
I also need to replace the manhole cover with the double sealed unit. Again, the top of this is flush with the surface of the screed.
Thursday, 14th June: I cut the DPM evenly all round the edge of the slab ready to overlay a further sheet of DPM underneath the insulation.
I used thick felt adhesive to stick the DPM to the existing house wall below the house DPC (which is only hot bitumen poured on the bricks anyway).
Friday, 15th June: I laid the second DPM and used the bitumen felt adhesive to seal it to the first DPM wrapped around the slab.
I then laid the 90mm floor insulation over the whole of the floor.
To get ready to lay the screed I need to plan the channels in the screed for both the central heating pipes and the waste pipes. To do this I need to buy the shower tray to see where the plug was located. Boy, are they heavy!

I also plan to screw battons to the walls to make levelling of the 60mm screed easier.
Saturday, 16th June: Using the laser level, I screwed battons to the long walls to act as levelling guides when laying the floor screed.
I chipped away the old outside inspection cover and placed the new double-sealed unit in its place. I won't concrete it in place until we have decided what we will use on the extension floor as this will determine the cover's final height.
A piece of wood placed on the battons on the walls shows that the height of the cover is just about as planned and there is just enough height.
I built some shuttering around the cover so that there is space left around it when I screed the floor. The cover can be concreted at its final height later.
I built some shuttering around the waste pipe from the shower which will run in a channel in the screed. I also drilled three holes for the two central heating pipes and the mains feed from the house.

On Monday I will cut and place the metal channelling as I have now bought the two radiators radiators needed.

Well, this is a bit of a screw up! I realised that could not connect the drainage from a washing machine and the shower to the same point as water from the machine will bubble up through the shower plug hole!

I need to connect them separately to the soil pipe.

Monday, 18th June: I cut and placed the in-screed channelling for the central heating pipes.

Notice the the single waste pipe connection.
This is the channelling for the 1m radiator - I've cut two pieces out for the exit of the pipes at either end of the radiator.

Building Control visit Stage 9 - floor insulation: The Building Control Surveyor came around today and Oked the additional DPM on the floor and the floor insulation.

He advised me to place some DPM on the door threshold which I had not done.

I think I am ready to lay the screed later this week.
Much of the day has been spent moving this...
...to this skip. I think I could spend my time more productively!
Wednesday, 20th June: We started laying the floor screed this morning after an early trip to B&Q to picked up sand and cement.

My wife mixed the cement and I laid it.
A little more area covered.
Three-quarters of the way there now!
Just the last bit to do...
Job complete!

It took 44 bags of sand and 7 bags of cement.

I used bags because it was more convenient to make the cement than using a jumbo bag and barrowing the sand to the extension door - it was more expensive though.
Copyright: Chris Gare 2007 - 2018
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