How to build an extension

Bowey123

I have architects plans for a granny flat. But I am wondering if I can save a bit of money by doing some of the donkey work myself then getting contractors in to do the rest.
The work is turning the garage, the existing kitchen behind that, and the existing utility room behind that into a granny flat. The rest of the downstairs is big enough for us. The only work to divide the space is to build a stud wall between the existing kitchen and the rest of the house. There is a door between the garage and the hall which is to be left.
My thoughts on the order of the work is as follows:

1. Do first fix plumbing
2. First fix electrical
3. Raise the floor in existing garage so it is level with the back two rooms. Would this be a joiner?
4. Get plasterer to put plasterboard throughout and skim. Put up stud wall also? Or is that the job of a joiner?
5. put up ceiling and insulate garage and utility room. Existing kitchen has a bedroom above so does not need roof insulation
6. Fit kitchen ( joiner)
7. Tile bathroom (tiler)
8. Second fix electrical Raise
9. Second fix pluming
10. Painting
    
    

Is there anything I am missing? Or have I got stuff in the wrong order?

Section62

https://forums.moneysavingexpert.com/discussion/6683841/how-to-build-an-extension

If you've not done building work before then you'll probably be best off getting a builder to do the whole job for you. They will sort out the trades they need for the different jobs.

If you try to project manage as well as doing some of the work yourself you are likely to come up with problems of people not arriving when they should be, and probably worse, people turning up before you are ready for them. To make this work you end up having a longer build time than necessary to allow for hold-ups. Getting the individual traders yourself may cost you more overall as some will charge you for a day's work for smaller tasks, whereas a builder may get a plumber (say) to fit several jobs in to one day. Traders may also quote high to allow for dealing with the hassle factor of a DIY project manager (and risk of non-payment), whereas they would charge less doing subbie work for one of their regular builders.

It makes more sense to take a semi-DIY approach where the project can be split into distinct sections - for example the builder hands over a plastered shell and you sort out the finishes and fittings.

Is there anything I am missing? Or have I got stuff in the wrong order?

Building regs?

Also have you checked the need for planning consent and/or getting permissions under covenants?

Heedtheadvice

I more or less agree with the above.

My first thoughts were, planning, building regs, finance. I assume you have dealt with those with action/advice from the architect...?

Following that a build spec based upon the consents to get quotations ( best get three) and then review and select one/negotiate any changes that may result (cost issues, changes etc, including allowances for contingencies).

Decide if you can proceed and if too expensive will the builder be flexible enough to accept some DIY and how you/ they will allocate responsibilities document the agreement with architect help? Mixed responsibility is a recipe for problems and as above no benefit for the risks it entails. That discussion will enlighteen you as to project activities/ flow and dependencies. That is for starters.

MikeJXE

The garage floor my not have a dpm and certainly not insulated

sheenas

Most jobs are pretty straightforward for an experienced diyer. The key element though is understanding in detail each job. Converting a garage property is need a correctly installed insulation system not just some king-span slapping up. I would insulate the floor for example. Consider how the heating is going to work all these things take time and research to do properly. The architect will know the answers and the builder will know how to execute the job properly and manage the labour. I suspect a good diyer could save 35%.

thegreenone

Where are you putting your new kitchen or will you share with Granny?

Silvertabby

https://forums.moneysavingexpert.com/discussion/comment/82141685#Comment_82141685

Not necessarily. It's an integral garage, as is ours, and the foundations/DPM/insulation are the same standard as the rest of the house.

We haven't converted ours, but several neighbours have, without any DPM/insulation dramas.

MikeJXE

I said the garage floor may not, there was no mention of foundation DPM, are you here to give advice or nit pick someone else’s ?

Section62

https://forums.moneysavingexpert.com/discussion/comment/82147583#Comment_82147583

You may have misunderstood Silvertabby's post. They weren't talking about "foundation DPM" - they were saying their garage foundations, and DPM, and insulation are the same standard as the rest of the house.

Most of us are used to garages being built to a much lower standard than the rest of the house, so Silvertabby's post is a useful reminder that isn't always the case.