epsilonGreedy

Do you mean flowcoat? There is a difference: https://forums.ybw.com/index.php?threads/the-difference-between-gelcoat-and-flowcoat.458139/

I agree with the sentiment but want to point out that some yachts are manufactured using a composite of grp sheathing over ply sheet. RM Yachts in france has applied this technique though it remains a niche option because most people spending £100k+ on a yacht share your concern that grp + wood sheet + water is not a happy combination. http://www.rm-yachts.com/en/the-concept

I think @canalsiderenovation should go back to the architect or person who produced the technical drawings, explain the lack of fall problem and then ask the architect what was the original designed height differential between the main tiled/pitched section and wall plate of the flat roof extension. My theory is that the GRP roofer is not the total incompetent as concluded so far and in fact he realized the main builder had bought the main walls up a few cm too high. Given the slim margin between gutter height of the main building and the finished level of the flat GRP roof, if the main builder errored how could gradient be created. Before proceeding with the supplementary pitched roof idea I would want an independent design from the architect showing details of the internal gully where the grp roof meets the tiled roof.

If the ground floor ceiling is not fitted you should be able to pin down the source of the creeks. In addition to prior advice I would investigate the joist ends and see if one joist is floating and not taking any weight. Retrofitting a few thin shims could sort this. In my previous house a copper water pipe was the source of creeks because this had been jammed against a joist. I would not contemplate putting the ceiling up with unresolved floor creaks.

I would have bluffed it and started a thread titled "Survey for Death Watch Beetle proves negative".

Now that summer has ended my plan is to put down the roof underlay asap once the trusses are up. This means I have to plan for a period of exposure before the roof is slated. Having trawled the forum for discussions on breathable roof underlay here is my short list. Tyvek® Supro/Supro Plus https://www.dupont.co.uk/products/tyvek-supro.html Weight=145g, Strength=245&300, Exposure=4 months Price £135 (ex VAT & 50m x 1.5m) Protect VP400 PLUSLR http://www.protectmembranes.com/uploads/ddd45e1cb3584a908c2ffb62079b4bb1.pdf Weight=197 or (170?)g, Strength=305&325, Exposure=? Price £86 (ex VAT & 50m x 1.5m) Cromar Vent3 Pro https://www.cromarbuildingproducts.com/wp-content/uploads/2020/07/Vent3-Pro-Breathable-Membrane.pdf Weight=166g, Strength=270&300, Exposure=3 months Price £86 (ex VAT & 50m x 1.5m) Should I add another product to my shortlist? @PeterWrecommended an underlay in a recent thread but I cannot find that.

8k for scaffolding on a fast paced project seems high. Bathroom budget looks low. I did not see a figure for a kitchen. Nothing for landscaping? As minimum you will need a mobility ramp and to cost in a drive in order to compare with other SQM figures.

@PeterWI am just catching up on old threads of mine. I recall reading your reply and wondering how I could end up with the wrong pitch as this is preset in the trusses. Is there another pitch, might you be referring to ending up with a roof that has a very thin row of tiles or likewise strange tile widths bordering a valley.

Thanks. I was concerned I might have to buy a roll width that was a nice round multiple of the batten centre distance.

@nod what type of ridge tiles can I see in that photo? Everyone I speak to locally suggests I use angled slate ridge tiles with the pronounce lip but I do not like the aesthetic result from a distance.

Looking at builder merchant web sites both widths of underlay are mainstream hence my confusion. I assume the fewer overlaps from using 1.5m rolls on a new roof is preferable. In the case of my hipped, L-shaped 30 degree pitch roof should I consider using 1.0m rolls? The felt might have to cope with a couple of months of exposure. Background Info: Cold attic space, 600mm truss centers and the felt will be drapped without sarking support.

Larger slates make a roof look more commercial. If 200 x 400 slates were mainstream I would select these for my roof as they give more of a heritage look, if this is the objective. One reason I have not confirmed an order for Nu-lok is because the system's reduced lap gives a roof a different look.

My trusses sit on the inner block wall so in theory the wall plate seat should be dry. Boxed eaves should help as well.

Treated/Untreated C16 or C24 Rough sawn so it grips the mortar bedding or just normal smooth wood I am also getting mixed messages on the thickness. Local trades assume 50mm is fine whereas technical resources indicate it should be 75mm thick. My wall plate is supporting trusses as 600mm centers, the inner wall blocks are fibolites (heavy end of light) and the roof cover is natural slate.

Although @ToughButterCupwas asking about rim wallplate I found an answer about minimum lengths for regular wall plates on the NHBC technical site. The minimum run should be 3 meters or supporting 3 trusses as already mentioned above. https://nhbc-standards.co.uk/7-roofs/7-2-pitched-roofs/7-2-6-wall-plates/ The same page also mentions a minimum thickness of 38mm timber whereas my technical drawings say 75mm and also above @PeterWsays 4x3 is becoming the norm.