To think I can design my garage extension without hiring an architect

[Pavementworrier]

Or am I kidding myself

I'm sure architects didn't used to be a thing normal people ever had to hire

We did a rear extension without an architect. We dod have a structural engineer visit but other than that had a good builder!

A loft conversion with an extension is more complex than a garage extension, which presumably, is a simple increase in footprint.

I’d imagine there are still structural loads to be calculated

My friend did this when applying for planning permission and it went well!

It’s all dependent on the size, but a simple single storey extension will generally not require calculations and a competent builder will have a working knowledge of spans, openings etc and when to involve an engineer.

Don't waste money on an architect! A lesson I unfortunately learnt too late.

Don’t skimp on this stage it can be costly

Don’t assume you can trust your builder - they will likely design what they want to build

Professional drawings maybe needed by the planning and building control depending on what you are having done and any restrictions on your property/area.

If you sell your house and the work you have done isn’t correct it can cause problems and result in a lost sale

Do you need to meet building regs or get planning permission? Do you need any expertise for either if these?

We used an architect for an extension, which was very similar to an extension that our neighbours have. We initially thought it would be sensible/cheaper to ask their architect to do the drawings, but we couldn't get hold of him, so ended up with our own architect. I'm really glad we did as our architect suggested a few other things and we've ended up with a better extension.

No expert but garages can be single skin possibly, rooms need a different spec and insulation.

If you want to sell the house, you need to provide proof that the extension has been approved by the Council Building control team. So I would start with a phone call to them to ask what’s required for your ‘vision’. You may consider it a faff, but it’s a whole load more faff if it’s not compliant when you want to sell it (it has to be done retrospectively, takes time and won’t sell until it’s done)

We did a loft conversion. Hip to gable plus dorma. No architect but I did a set of drawings myself to show to a planning officer to double check we were within permitted development and to communicate to the builder. We did pay for an engineer to calculate steel size etc but that was a fraction of the cost of an architect.

Out of interest was the garage insulated and correctly waterproofed? or did the builder just add plasterboard to the walls?

You can’t change a garage into a room without planning permission as the spec is totally different. If you proceed without permission and expert advice (architect/structural engineer etc) you’d be very foolish.

Theres a reason architects exist and (contrary to your weird idea) they have for hundreds of years.

This is not correct.

Most garage conversions do not need planning permission. You might if there are permitted development restrictions regarding changing the door to a window, but this is unusual.

The vast majority of garage conversions need only an application to Building Control to ensure they meet the standards for a habitable space. Most people do this via a Building Notice where only 48 hours’ notice prior to commencement is required. Absolute waste of money to involve an architect for something like this. A competent builder is all you need.

how are you assessing if the person is a competent builder, anyone will say they can do it, and before you know if you have mouldy walls and it all has to be stripped out because the insulation wasnt installed or specified correctly.

Agreed. A friend successfully submitted her own drawing to planning for a garage. Edit: I mean building control, not planning.

I think what people are missing here is there are things that need to be resolved / decided before approaching a contractor. Potentially, depending on where your property is located, you may require planning consent. Most Builders will struggle with this, and if you dont get it and should have, then you are likely to get an enforcement, and then have to remove the works, at your expensive, not really work the risk. Then you have achieving building regulations for turning an uninsulated, most likely solid brick space into what is legally considered a habitable room. The floor is almost certainly uninsulated, so you will need to attach maybe 100mm insulation plus screed and floor finish, creating a change in the floor height, do you have a step as you go into the space, does the old door still work, etc. Next is the walls, if these are solid brick, single leaf they need to be insulated to achieve Part L, again looking at roughly 100mm insulation, but it needs to be appropriately spaced from the brickwork to allow it to breath. the roof may also need insulation between joists etc. all need to be calculated and specified, otherwise you are open to the whims of a contractor without any instruction. They may very well go and add insufficient insulation or install it incorrectly, which could lead to damp problems in the future, these wont show up for a year maybe, by which point the contractor has disappeared. you now have spent £10k on a space that needs to be completely redone. Yes you can always do it yourself, but the purpose of a designer, is they are taking responsibility for it working and being complaint. the contractor then has a very clear set of instructions. I think anyone who has ever been burned by a contractor would agree, you are far better off spending the extra £1-2k for a designer on a construction project, who helps you manage everything, than going straight to the person who just wants to build it as cheaply as possible to make a profit.