Understanding Building Regs Requirements

Toolguy

I'm in the process of putting a second story on an existing dormer bungalow (and building single story kitchen/living room on the back), and am now at the insulation stage.
I'm wondering whether to scratch coat the inside external walls before putting up the insulated slab, or not, and have received a lot of conflicting advice (cavity has been filled with beeds). Regs call for 83mm, but thinking of using a 50mm slab.

The main point is I'm gonna live in this house til I keel over, so not that bothered with BER ratings, but reading on the forums here, I hear a lot about building regs. As it's not a new build (and I've no intention of selling) should I be really be worried about regs and how can they affect me? Up to this point I've followed all the regs.

sydthebeat

"building regulations" is not something you can decide to be worried about or not.
They are legal requirements and if you dont meet them you are breaking a law.

If you dont have professional involvement on the build to advise you of how to meet these building regulations, then its up to you to know and understand the regulations and know how to comply. Ultimately, non compliance with building regulations falls upon the building owner.

The good news is the 'insulation' building regulation requirements for extensions and material alterations are a lot less strict than they are for new builds.
see from page 25 onwards here

and remember, 'insulation' regulations are only one of 12 different regulatory documents that have to be complied with.

Toolguy

Thanks Syd,

I'll have a read of from Pg 25 on. Appreciated.

What I'm wondering, the floor joists were 4.5 inch - I've changed these to 9in, but would there have been a requirement to do as, as they were in the existing building? That's sorta what I'm getting at re: regs.

Gumbo

Toolguy wrote: »

Thanks Syd,

I'll have a read of from Pg 25 on. Appreciated.

What I'm wondering, the floor joists were 4.5 inch - I've changed these to 9in, but would there have been a requirement to do as, as they were in the existing building? That's sorta what I'm getting at re: regs.

That's a structural question and your Engineer determines what size and spacing of joists are required.

its worth noting that the regs don't state what insulation is required and what size joists are required. There are calculations to be done in order to meet the minimum u-value and air tightness required, even on extensions.

Toolguy

Thanks Kceire,

The guy doing the insulation told me 83mm slab was compulsory, but I want to only use 50mm (cavity has been filled, and I'll scratch underneath the slab, so u-value should be okay). It's a bit of a minefield working out what is a reg and what is open to interpretation.

Gumbo

Toolguy wrote: »

Thanks Kceire,

The guy doing the insulation told me 83mm slab was compulsory, but I want to only use 50mm (cavity has been filled, and I'll scratch underneath the slab, so u-value should be okay). It's a bit of a minefield working out what is a reg and what is open to interpretation.

It's not really a minefield. Just do the U-Value calculation and that will tell you the minimum amount of any particular insulation board depending on its own official R value.