Knocking through to garage and converting half to an office - Building Control If you want to know how your DIY projects could be affected by building and planning regulations, click here to post questions and view answers

[m4rrk0121]

Hi,

Apologies if I'm asking something covered elsewhere, I have searched and couldn't find quite what I needed.

So I have a 2014 Redrow and I have knocked through to the internal garage. To do this I had to go through the fire rate plasterboard and I put lintel in etc, I'm using a fire door and frame....basically I think the doorway is good.

Now I need to build a stud wall and plasterboard the half of the garage but I have a few things I am unsure of:-

- One wall backs onto an internal house wall so I guess this can just be plasterboard without insultation?

- One wall is an external cavity wall. I guess this needs insulating but what spec would I require? link to a product would be really helpful.

- For the stud wall I guess this needs the most insultation. Is any particular spec required and does it need to be fire rated?

- I don't have a step down after knocking through to the garage. Is it sufficient to use underlay with a DPM?

- Lastly, there won't be a high difference between the new space and the remaining garage on the other side. Is this a problem? Do I need a course of bricks in case of a spill?

As you can see I'm pretty clueless so any help would be massively appreciated :)

[stoneyboy]

Hi m4rrk0121
As a general guide you will need to add 120mm+ of celotex insulation added to the outside wall (assuming there is no insulation in the cavity) and the stud wall. The stud wall should be fire resistant and you should probably add insulation to the floor.
You must agree your spec with the local Building Control Office either by submitting plans or by the building notice method but note the latter is difficult with covid around.
Regards S