goodbyegti

Sorry to hear that and good luck! Great info eg. use of Strava! Thanks for sharing.

Surely it's fine. The advantage you have is that you can inspect it easily in cold weather for condensation. Perhaps by cutting a small hole in the foil and taping it up.

Good to hear! Are the joists in the correct place? It's worth checking you have enough upstand on the parapet after the extra 50mm goes on top.

We had the same spec. The tape doesn't even stick very well and melts off in the sun. I had to keep patching more on. Tongue and groove boards seem a much better design. I just can't imagine the tape sticking for long. Our builder washed the 10mm cavity with a hose to keep it clear. Not that it mattered a huge amount with the render.

To follow up on this, I took your advice and asked the engineer. £350 later he said I can use 2 No.x 45 x 195 c24 joists glued and bolted to hang the staircase trimmer off, and 3 studs glued and bolted for the support post. So all-in-all the end result looks like my drawing above, but I can use 45mm wide joists, rather 63mm. BCO is happy and has accepted, so it will soon be time for some demolition 😁.

I would guess the slab is approx 150mmm

Perhaps you could flood the balcony with some food coloring / tracer dye and see if it shows up inside?

We used 90mm k106 with a 100mm cavity. The builder had no issue keeping the cavity clean. I think he hosed it on the odd occasion. The negative was the breathable tape for the joints. It cost loads and didn't always stick.

I guess you could glue the ply/pir/osb sandwhich together. Not sure I would want to try it!

I agree generally. I guess if water got under the stone then ice formation could lift it.

For interest, here is my parapet. The silver flashing tape is temporary and will be replaced with lead. The wall is 100mm thermal block, 90mm phenolic board, 25mm surecav, 125mm stone. I have a GRP roof (2 x 450gsm) which comes up one side of the parapet. There is a cavity tray so far, formed from a DPC. The stone masons did something crazy with the weep vents, but seem to work well enough. They also ordered the wrong size coping stones, so I need some wider ones.

How do people fix down their coping stones when you're supposed to have a DPC underneath them? Everything I can find seems to involve drilling holes near the mortar joint between coping stones. Eg these things (where is the DPC!):

Why would it get damp there? It's below the insulation and 'warm'.

Correct, all wiring below VCL. Not much room. You can see the void in the diagram.

That's actually what our architect has specified for our warm roof. On top of the OSB deck we have 150mm PIR, then a loose fill between the joists underneath with mineral wool. The joists are boarded over on the underside with 18mm OSB, then a VCL, then battens to form a service void, then plasterboard.

Many thanks! I have a plastic surecav cavity spacer in this case, so I think I can screw extra ties in through the pods. Unfortunately the up and down range won't be as good due to small size of the pod.

As per the title, the stone mason cladding my extension asked if he could borrow my angle grinder to cut off some wall ties in the way. I was thinking it was just one or two, but it was the entire row along the wall 🫣.. His problem is that because it's natural stone, it's hard to always get it to line up with the ties. I think it's the first time, I've seen most get used. Thoughts on remedial ties, or am I obsessing?

Thanks both. Points noted for next time. I'll do my best to encourage better practice.

Should I worry about gaps between boards like this? Personally I would be filling them and taping the boards together, but the day job prevents!

I'm trying to squeeze part of the bathroom below the upper flight of stairs. The design of the stairs can't really change as it's a barn conversion with confined headroom. Here are the stairs: And here are the dimensions of the aperture: The upper floor consists of 195mm deep joists at 30mm centres. If I consult a span table like in the attached leaflet 8, I get: Span A = 2230mm Span B = 825mm Span C = 2035mm A/B = 0.19 The table in leaflet 8 tells me that I can use 2 No. 38 x 195mm joists for a span S of 3.73m. These would actually be 4530mm long in total, supported by a post underneath. To be clear I'm talking about the doubled up joists on the right of the technical drawing (not the horizontal trimmers). The calculations rely on the posts within the stud walls below, supporting the joists above. These posts would be 3 No. 95x45 mm studs bolted together and would form part of the stud walls on the ground floor. To further complicate matters, a stud wall (upstairs) also needs to be supported directly across span S, so I could use 2 No.x 63 x 195 joists instead? Will building control shoot me on the spot? The wife says I should get off the computer and consult an engineer? Leaflet-8-Timber-trimeer-beans-and-joists-sizes-and-details-for-trimming-around-openings (1).pdf

I can see that now the wall is going up! I have nightmares about mortar droppings. Builder is cracking on at least, and looks good so far.

It's been contracted out. The tolerance is much larger than 25mm. It has to match the stone wall on the existing building.

Thank you for the insightful comments. As far as the design goes it's too late to change, but good to know for the future. Radon appears to be a moderate risk in north Bristol. To be honest, I hadn't even thought about it. The stone going up on the outer skin is as pictured. I suppose the SureCav at least gives a flat surface to lay it up to.

Thanks! That's also suggested in the SureCav diagram - makes sense to me.