Advice - Building Regulations

[peter88uk]

Hello,

Hoping someone can give me some advice. We are going a partial garage conversion (rear of a attached tandem garage).

We've submitted the plans etc but they have come back and said the following '..your external wall specification to be acceptable then it needs to be proven that the property can be classed as sheltered in BS 8104:1992.'.

I've had a look and it's to do with driving rain. The wall is a solid brick and block wall that we have planned to put Celotex PL400 onto to meet the target U Value.

I assume the lack of a cavity is the issue so i'm trying to figure out our options.

I will call BC tomorrow but I thought I would see if there are any suggestions/advice from anyone on here?

Thanks.

 

[freddiemercurystwin]

Is it brick or block? Is it rendered if block?

 

[peter88uk]

It's brick on the outside, then block on the inside - with no cavity. No rendering.

Thanks.

 

[freddiemercurystwin]

Normally a coat or two of RIW (bituminous paint) before you batten and add your insulation is enough to satisfy most Inspectors.

Untitled

• freddiemercurystwin
• 18 Jul 2010
• 7

A little debatable whether it needs it as its double skin but its not expensive to do (in fact its cheap compared to trying to remedy afterwards).

 

[peter88uk]

Thanks freddymercurystwin.

BC are aware it's double skin. Hopefully a few tins of that will be sufficient then but i'll confirm this when I call them tomorrow. Thanks again for your advice.

 

[^woody^]

Can't you just establish that it can be classed as sheltered in BS 8104:1992?

 

[peter88uk]

Can't you just establish that it can be classed as sheltered in BS 8104:1992?

I am looking into this. I've been give a load of figures/calcuations by a surveyor in the family, although I can't make much sense on them to be honest. I final figures seem to be:

Wall 1:
Dws = 0.36
1/m2 per spell

Dwa = 1.44
1/m2 per year


Wall 2:
Dws = 0.72
1/m2 per spell

Dwa = 2.88
1/m2 per year

Don't know if this means it's sheltered or not!? Hoping BC could answer that for me tomorrow.

Can anyone offer any advice regarding this?

Thanks.

 

[peter88uk]

I'm still trying to determine if it is classed as sheltered or not (the one wall is actually shelter by next door anyway!). Hopefully I'll hear back about that today. (if anyone can make sense of those figures that would be great.).

Having briefly spoke with BC I was told that just putting bituminous paint wouldn't be sufficient and he ran through an option that is commonly used, i'm not 100% sure on all this as I didn't get chance to write it down as I was at work, but it involved bringing the DPM up from the floor and rough onto a sole plate, then installing the insulation an 1inch from the wall (creating a cavity), then putting another dpm on the wall so any moisture would not reach the insulation. Something along those lines but I need to get it clarified.

Thanks.

 

[freddiemercurystwin]

I have had the spec as previously posted on that drawing approved countless times by BC and in Plymouth where exposure level is considered severe.

Though one time an inspector asked for special fixings as the RIW is penetrated.

 

[peter88uk]

Thanks freddymercurystwin.

I will put forward the drawing that you posted to BC and see if that will be sufficient to pass based on that spec.

 

[peter88uk]

Thanks freddymercurystwin.

I will put forward the drawing that you posted to BC and see if that will be sufficient to pass based on that spec.

Unfortunately they have turned down this specification as the screws holding the battens on would rust if water penetrated the wall...

They've said they will discuss options when they visit next week.

 

[Deluks]

Unfortunately they have turned down this specification as the screws holding the battens on would rust if water penetrated the wall...

That's hilarious, and in any case, have they not heard of stainless steel screws?

 

[freddiemercurystwin]

As mentioned this can happen when you get an overzealous inspector:

Though one time an inspector asked for special fixings as the RIW is penetrated.

In that situation I specified special fixings, I shall dig the spec out later if you wish? They weren't cheap though.

 

[peter88uk]

As mentioned this can happen when you get an overzealous inspector:

Though one time an inspector asked for special fixings as the RIW is penetrated.

In that situation I specified special fixings, I shall dig the spec out later if you wish? They weren't cheap though.

If you could that would be great to have. Thanks

 

[freddiemercurystwin]

This was my response to the Inspector and the detail was subsequently approved:

We have specified 2 layers of RIW on the masonry wall prior to attaching the battens. If you believe this to be insufficient we can specify that a waterproof fixing such as Newlath Multiplugs is to be used to fix the battens to the masonry. In essence these are completely waterproof rawl plug type fixings that completely isolates the masonry from the battens. Normal hammer-in fixings or screws can be used. The screws are not able to come into contact with the masonry so there is no chance of the screw corrosion. See link http://newton-membranes.co.uk/wp-content/uploads/2011/05/Datasheet_NusealMultiPlugs_Aug09.pdf[/i]