Russell griffiths

Lean over the cavity every night and check with a torch, knock any off with a bit of stick. You shouldn't really get snots with a wire tie.

Ask them to install coring holes so the cavity can be cleaned out.

Buy your own materials and do it yourself. What is the reason for wanting this for an extension. My thoughts are that you will create a lot more agro than you need, the difference in materials from the old to the new will be a pain all the time.

That’s cheap loads of people on here paying double that. I didn’t have one as I was going to pile it anyway, why not phone a few companies and just ask for a soil bearing test, you will probably need to do a site strip so your down to bearing soil before they come out.

Rockpanel looks nice, bit expensive but no maintenance. I used on my last place cement sheeting boards that had plastic joining strips, made by James hardy. Its the details like this that this country lets you down, loads of other options available abroad, but over here if you want different it’s going to cost you.

Or as Simon pointed out, remove the two vertical timbers in my drawing and drop the stud wall down to fix the rim board to, this will tie things together nicely.

Don’t like that idea pain to build, where would you put insulation? not really understanding how the joist is attached. One question that would really affect how you build this would be if you want to leave the down stairs room Undisturbed, with my first version you will end up cutting into the downstairs ceiling, not a problem if your ripping it all out.

not to scale, and you will obviously need to check with your structural engineer regarding loading, but I think this will be easier to build, your original ideas will be a pain to air seal and insulate well. Cutting the joists back short will allow you to install a rim board that could have a VCL stapled to it so when you build the upper storey you will have something to tape to. 1. New wall 2. Joist hanger 3. insulation just me thinking out loud.

If you go and get a length of pipe 150mm and cut it into 600mm bits you can do a sleeve over your pipe and surround in concrete.

Having the bend collar protruding above the beams is exactly what you do, you will have at least 150mm of insulation above the beams so plenty of room to adjust to what you need poking up. You should ideally have the beams design done so that a beam doesn’t sit directly over a pipe. In the grand scheme of things a 110mm opening doesn’t even need a lintel as long as there is no direct load over it.

No ones answering so I will get the ball rolling. I think your ideas are flawed in nearly every aspect, the u value your looking at is pretty poor, I think your heat losses down will be large and you will spend half of your heating bill heating the gap under the floor. Are those plates designed for ground floor ? I thought they where used more fore first floor. If they are designed for ground floor then there must be a design spec for them. The problems you will have is stopping heat escaping downwards, (obviously) but also the airflow and drafts under the floor will be large so sucking the heat from the floor above. The majority of builders wont have any idea on the details required to make this work. What sort of depth are the joists?

I would get the price of the steel and fabrication down, and then use the saving on galvanising.

There’s normally lots of room for the rest bend as you have the depth of the beam to play with.

Why not get all the materials brought through and put on the grass, then you can rip the lot out to see what your doing.

Where are you @ToughButterCup.