Do I ask for a rework? :/

[Jimbo37]

Hi Self Builders

A bit of a problem, that I'd like your thoughts on, please. Im building a flat/parpaet roof house with , which calls for preservative impregnation where the roof timbers enters the external walls (of cavity block walls). The builder placed the timbers today, and built blocks between the timbers and one row on top, but without the preservative, nor did he wrap them in DPC - there are 2 more rows of blocks to go to take it to the top of the parapet. Is this a serious omission, do I get a rework? Is there some other mitigations, other than a rebuild that I could ask for, that would suffice? Clearly, if it must be done, I'll ask for the preservative and rebuild - but I want to be reasonable, if there is another sufficient answer.

Edited July 28, 2023 by Jimbo37

[Bonner]

Never seen this on a drawing. Assuming they are built into the inner leaf of the cavity wall, it is the same as floor joists which are not treated. Just make sure the cavity tray is installed, then it will be fine.

[saveasteading]

I dont know whst the rules are, but i would always use treated timber where there is any chance of damp. The extra cost isn't huge,  it keeeps away woodworm too.

As a compromise, the ends could have been treated on site. That woudnt be "impregnated" though.

 

Bottom line: it's on the drawing.

 

No insulation in the walls?

[Jimbo37]

1 hour ago, saveasteading said:

No insulation in the walls?

Yes, the cavity is filled with bead. That reference is out of shot

Edited July 29, 2023 by Jimbo37

[saveasteading]

Just now, Jimbo37 said:

the cavity is filled with bead

Does bead keep dampness in the outer skin. I guess it does, as any water will trickle down and away.

[Jimbo37]

Yes, that is my understanding. I suppose that the dpc just above helps with keeping weather wet away. On the other hand, I think it is a condensate point so the route/trickle out is a thing that will be used

[Jimbo37]

Can I approximate your thinking - it is probably OK? @Bonner and @saveasteading

[Dave Jones]

you need a tony tray

 

http://tonyshouse.readinguk.org/tony.htm

 

[Jimbo37]

I just nipped up for a closer look & there are another couple of issues that veer slightly from spec, which are of no consequence, except they add to the condensation exposure of the end of the joist. (1) all joists project into the cavity by between 10 and 30 mm, and (2) the cavity tray is two courses (440mm) higher than it should, increasing the condensation area above the joist.

Two sketches attached - the specification, and the as (nearly built) and my proposed mitigation - essentially to drape a DPC over the end of the joists (the blocks with the Xs are not yet built)- thoughts?

 

 

 

 

 

Edited July 29, 2023 by Jimbo37

[Jimbo37]

10 minutes ago, Dave Jones said:

you need a tony tray

 

http://tonyshouse.readinguk.org/tony.htm

 

I'm trying to avoid a rework, and cant visit a new spec on him - but thanks for the suggestion. Intresting solution though.