Insulation, UFH, conduit and Slab
Entry posted by Jenki in The Windy Roost Slab.
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Day 31 of the build. (this is taken from the day we started shuttering the foundations)
The weather up North has been spectacular for about 3 weeks, so we (Mandy and I) pushed to prepare and pour the slab before the weather changed, as I'm sure we will get a few weeks of low pressure, wet changeable weather after this spell.
Following on from the foundation ICF walls, I'd already loaded around 20ton of 40mm to dust in a pile the slab area. Sat on the sand blinded radon barrier.
Job one was to sort the drainage. I'd posted previously about my plan, and some constructive comments suggested changing my planned route, but with the extra length of run to the drain invert level I would have had to increase the floor height even more. So stuck with my original sketch. We ran string lines to mark the main areas, namely WC, SVP in the plant room, shower, WC and Bath, a need ran the drainage to the locations, as the utility backs onto the plant room I didn't add a drain in here as I'll run through the stud and use the SVP. Once the drainage was in place and is tested. We spread out the hardcore and compacted it. I used 10mm crush and run to bed the drainage and cover the pipes, I also ran ducting at this level, bringing in water, power, treatment plant feed plus some future ducts.
To get the hardcore level / flat I used 3m lengths of galvanised conduit set on mortar pads all level to each other and used a 4M ally beam to screed the slab.
I compacted the first layer then used another screed pass to fill in any deviations and used this as the level for insulation.
I used a combination of 200 mm EPS 70 (50mm sheets and 100mm sheets all layed to stagger the joints, and used foam to seal to the ICF.
The top layer was 100mm EPS150 this gives a firm hold for the UFH staples, and a firmer feel to the insulation layer.
We plan to use a large shower tray and have this level with the floor, so I made this area sunken with two layers of EPS150 and a layer of 50mm PIR.
As we were installing the insulation I installed 2 * 100mm ducts for the ASHP in the second layer of insulation these were only 800mm long, and a duct for cables.
I also added flex ducts in the insulation for Hot & Cold services to the kitchen, utility, WC,Shower,bath, all these were cut using a hot knife.
Lastly I cut some pipe for floor sensors in the kitchen, lounge, bedrooms and bathroom.
The underfloor heating consists of three loops around 95M length, planned using Loop cad.
The manifold was plumbed , filled and a pressure gauge to ensure no leaks. We have good water pressure so could pressurise to 6 Bar. ( With the heat ☀️ this rose to 9 bar one day).
The above picture also shows K Steel screed rails. I used these to break the slab into smaller bays, and mainly will be under stud walls. The slab will for the foreseeable future be our finished floor, so I wanted to introduce expansion joints and force any cracking to these locations🤞.
I also used Tibmix metallic dry shake topper on the concrete, the dry shake should help suppress the fibres and also increase the surface hardness.
The pour happend on Friday 16th June, the first 5cube arriving at 8.30. we did the kitchen bay first which needed the 7t 360 to move / place the concrete, then, poured the WC / plant room and utility bay. This was an error, I wanted to pour the lounge next so both bays could be finished at the same time, but under the pressure of the pour took advice to do the awkward section next. This resulted in only a 3rd of the lounge bay having concrete, so this was spread out lower so the next load could fill the bay.
By the time the second load arrived, the kitchen and utility bay was ready for power floating. The pan worked well and I had some time to start edging the slab, the rebar didn't allow the power float to get to the edge of the slab.
By 13.00 all bays were in and leveled, but not floated, but the sun was very hot, and the kitchen bays was getting hard rapidly, I managed to float this but was struggling to to get a perfect finish.
To dry shake makes the surface hard and this was apparent, the lounge and bedroom bays floated better, and to the main the dry shake suppressed a lot of the fibres but there are still some visible. The kitchen bay was rock hard by the time I managed to float again, and although it is fairly flat you can see, but not feel, the path of the power float.
I used Setseal 6 as an acrylic sealer, which seals the surface and aids the curing process. By the time we finished the floor was rock hard, I mean hard, the idea being that the slab will slowly cure now but will not be affected by rain etc. Time will tell.
Due to the temp, and the float not getting to the edge, I will have to carry out some remedial work on the edges of the slab, as by the time I go to troweling these it was too late.
Today the slab looks great, it's flat and level, but the perimeter 2 inch will need some polishing, as will a section in the plant room.
I'm confident I can get this fixed. Time will tell.
The following picture doesn't do the slab surface any justice. It looks rough, but it's glass smooth.
So 10.5 cube of fibre reinforced concrete. Power Floated, and this was non stop until 17.30.
My chest and fore arms are wrecked from trying to tame the power float.
I'm a little disappointed in the edge finish, but looking at it another way, it's way better than if it would have started raining, or the wind that we have today. I'm sure a few hours with a wet diamond polisher will rectify the edges. Maybe another hand would have been good. 🤔.
Onwards to the ICF walls...
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