Internal wall insulation question

wazzoraybelle

I'm hoping someone here can put my mind at ease. Any input is welcome.

My builder is building up an internal wall insulation detail in our retrofit of a rubble and mortar built house. One of the stud walls is structural holding up one side of the upstairs floor.

We have been doubting the quality of his work for some time and hope someone can shed some light on somethings for me. He is using 100mmx 38mm at 600mm centers with C16 timber, (this then has insulation in it and is clad in 9mm OSB on the warm side). It doesn't appear to be pressure treated but he has painted it with preservative. My questions are these:

Is the timber fine for this purpose?

Is there a requirement for the timber to be pressure treated ?

The stud rests on a heated slab and there is a strip of what appears to be breather membrane between the stud and the concrete. Should this be DPC?


Thanks,
Wazzo

Sir Arthur Daley

Have you an engineer on the job?

wazzoraybelle

I do but he hasn't inspected the wall and is abroad for 2 weeks. I'm afraid that when he returns the wall will be all clad.

I'd also like to be a bit informed myself when I talk to him.

Sir Arthur Daley

You are paying him big money no doubt to see the job right so get him on site tomorrow, he will know everything.

archtech

WikiHow wrote: »

You are paying him big money no doubt to see the job right so get him on site tomorrow, he will know everything.

How do you know that the engineer is been paid big money? Or what level of service was agreed between the parties.

Did the engineer furnish the builder with a detail/ specification for the wall buildup? It's upto the engineer to satisfy himself that the builder has done the job as directed/properly, otherwise in the event of failure he will be liable. I assume there was a building contract between the builder and client.

Sir Arthur Daley

archtech wrote: »

I assume there was a building contract between the builder and client.

We cant assume anything, the OP will need to provide us with more details of his contracts.

BryanF

wazzoraybelle wrote: »

internal wall insulation detail in our retrofit of a rubble and mortar built house.
1. Is the timber fine for this purpose?

2.Is there a requirement for the timber to be pressure treated ?

The stud rests on a heated slab and there is a strip of what appears to be breather membrane between the stud and the concrete. Should this be DPC?


Thanks,
Wazzo

1. Yes & 2. yes

With the limited info I'm not confident of your engineers approach.
Tell builder to prop wall until eng returns. Written instruction.
Rubble stone walls require more consideration than this.

Edit- is there a spec, what does it say?

wazzoraybelle

The stud wall was very ad hoc and I havn't been given any details other than what I've discovered myself. I don't think there was any spec drawn up, The Engineer is away and uncontactable at the moment.

I found that the rigid insulation was put in deficiently and have asked the builder to remove the OSB cladding and fix the insulation. This remediation work is about to start. When the cladding is removed the stud will be exposed and I'm hoping the engineer will be back to inspect it before it is clad again. I don't want to delay the builder further unless it's necessary.

The reason I am suspicious that the stud hasn't been pressure treated is that they have painted preservative on it. might it be a belts and braces approach?

Can someone post a regulation that states such a stud needs to be pressure treated?

Thank you

wazzoraybelle

I should add that the stud wall sits about 50mm in from the external rubble wall but this wall is quite wet from exposure

barfold

just a quick question related to the op's question. Is there a regulation stating external timber walls should be pressure treated. I worked on a stick built house, 9x2 frame to allow for 200mm insulation ( timber frame companies only did 6x2 frames) and archirect only wanted nsole plates and heads painted with protim. He felt all pressure treated posed potential health issues. I found this strange as house was cladded with slate with no external leaf of block. Any opinions?

BryanF

barfold wrote: »

just a quick question related to the op's question. Is there a regulation stating external timber walls should be pressure treated. I worked on a stick built house, 9x2 frame to allow for 200mm insulation ( timber frame companies only did 6x2 frames) and archirect only wanted nsole plates and heads painted with protim. He felt all pressure treated posed potential health issues. I found this strange as house was cladded with slate with no external leaf of block. Any opinions?

Ah look we may not agree with certain practices but we're not about to start criticising hypothetical finished projects where the construction situations aren't clear...