Dave Anderson

Thanks Russell, I can see that would be a smart option

Revisiting this old thread as I have the same issue. Prior to floor screed I put in 25mm PIR perimeter insulation, against the patio door frame. Now, as the carpet is to be laid next week, it occurs to me that they have nothing solid to glue the grippers to. So I think I will have to dig out the PIR, fill it with self levelling, and rely on the thermal properties of the door frame to avoid a cold edge to the screed. Is there a "normal" solution to this issue?

Good point, thanks savea

Were actually using traditional hand trowelled screed at 60mm. But anyway I accept that 150 kg/M2 screed should sort it. So I might revert to a single layer of PIR as cheaper and quicker.

That's reassuring, thanks Nod

Thanks everyone, a variety of ideas all with much merit I think. I guess there is also the option of adding some self levelling, but with an area of 160m2 it's a bit pricey (Toolstation £500 at average 3mm thickness) so prefer to avoid if possible. I think I'll aim to persevere with chopping out the globs of grout as best I can with the Mutt and a chisel, then try "screeding" some soft sand into the low bits. Then let the PIR bend/crush to the shape under the weight of the wet screed. Unless anyone has any more suggestions? Still to decide whether to go with two 60mm layers of PIR.

Thanks for the idea Russell. Had a quick look and there seems to be a few 110v machines that might do it. Just wondering what sort of machine worked for you? Did you use something like this (I think you have to by carborundum or diamond blocks for it) or this or was it a heavy pneumatic scabbler?

Ok thanks I'll consider that - but probably will cost a bit more. So would you not bother with sand?

Hi all, I've read a fair few threads on here, but still have questions! Any advice will be much appreciated. Our builder has done the shell of our self build bungalow. They have grouted the beam and block nice and solid, and it's now over to me to do the DPM, 120mm PIR and 2nd membrane before the heating company do the UFH. But brushing-in the cement grout has left ridges up to 10mm high. I have begun breaking off the worst ones but it is very tough and impossible to get completely level. I'm worried about the insulation rocking or sagging, and any such movement inducing cracking in the screed. The builder has said it is usual to blind the floor with sand to take out discrepancies in level, but how would you get the sand level? Spreading the sand and dragging a straight edge over it? Once the DPM is down it's too late to adjust the sand if a PIR board is found to be rocking. Can anyone advise how to get this right?

Thanks Dave, so something like this... It looks like you'd have a small piece of the stub cill visible below the aluminium? Maybe a bit messy, but as long as the supplier can colour code it to the door frame it might look OK? Because we will have cut stone surround to the door I still think it might be neater to use a matching stone cill and just try to keep it clean. Then just decide whether I need positive drainage in which case just leave a 10mm gap with a channel below as per original post, or rely on the porch to keep the area relatively dry. Thanks again for your reply.

I assume the Macclex threshold will have drain holes out the front. So I think as Russell pointed out the door is sheltered by a porch I can rely on any relatively occassional wind-driven rain emerging onto the stone cill, then running away due to the slope of the cill and paving. I have therefore removed the drainage channel, allowing me to build up some extra blockwork to provide better support to the stone cill. I've also filled the cavity with concrete up to top of beam and block, to support the Compacfoam. Have I missed anything regards damp proofing? This design really just relies on the DPM wrapping up against the outer skin of blockwork. I've also removed the DPC under the stone cill, which didn't really seem to be doing anything. Is this OK? I'm wondering whether I can get the Compacfoam, being lightweight, to sit down tightly onto the DPM. Or will any creases in the DPM hold it up enabling it to then move under the weight of people on the door threshold? I'm thinking perhaps I could insert some threaded bars (as indicated on Compacfoam's website) and weigh the Compacfoam down whilst the screed is being poured. Any thoughts appreciated.

Thanks bassanclan, I'm sure that would look better. Only concern might be if any water does get into the threshold strip, where can it drain to?

Umm, fair point. There will be an oak porch, but with open sides, so some rain will blow in. The roof of the porch is 2.6m wide, so about 0.9m past each edge of the door. So probably unnecessary then. Thanks for flagging that up.

Thanks Russell. I've been a little concerned about the stability of the stone cill - if someone put all their weight on the leading edge it will tend to rock. I suppose the stone jambs at each end of the cill should hold it down ok, but I might pull the drainage channel forward and make sure it is offering some additional support.

Hi all, Our new build bungalow is underway - walls are up to DPC and beam & block is in. I have been puzzling for ages over the front door threshold. I have read a lot of posts here and elsewhere, and nothing ever quite fits my scenario. I have tried to understand the principles and have come up with my own detail which is shown below. I would appreciate any comments, criticisms or advice anyone can offer. Balancing insulation requirements, airtightness, watertightness, structural needs and aesthetics in a level threshold design seems to be a black art. We have no architect on board - we have preferred to carry out all design work ourselves (for better or worse). We have a masonry cavity wall with 150 cavity (50 air gap and 100 PIR). The outer skin is natural stone, with cut stone window surrounds and jambs to the front door. I do not like extended aluminium thresholds so am proposing a cut stone cill as shown. Endurance have shown me a number of their threshold options, the neatest of which in my opinion is a Macclex section which has a minimal aluminium projection externally which should throw water down onto the stone cill. The thing I am struggling the most with is providing adequate structural support to the threshold. I want to position the frame 50mm into the cavity, so it will not really be supported by the stone cill. I don't want to widen the stone cill to support the threshold, as it would be a cold bridge. Compacfoam or similar seems to be the way to go. But what supports the Compacfoam? This is solved in my design by filling the cavity with concrete to beam and block level and sitting the Compacfoam on that. Many thanks for reading this. I'd be very grateful for any comments or pointers.