Garage DIY refurb, advice appreciated

[bobbydigital]

Hey everyone, long time lurker first time poster.

Looking to refurb my garage for as little as possible so going to do full DIY refurb on it. I'll give a brief run down then ask some questions.

Looking to replace the old asbesto/cement roof, by replacing with a flat roof. The approach I'm taking is to take off coping stones, bed some wall plates on each wall, strap them also and then attach/sit the joists from one wall plate to another. Use firrings to get the required slope then osb and probably just a 2-layer felt system for now.

My plan however is to get 4.8m lengths of wood and leave the excess overhanging into my garden so I can then build a wooden workshop on the side of the garage so they share the same roof. Once the workshop is built the plan would be to take out a bunch of the wall with the correct rsj or lintels to create a bigger work space.

Excuse the mess of the courtyard/side garden I've just ripped up a decking, junk to go to skip that there is no room in the garage for and the plan is to sort it this year (pull up all the slabs etc).

I suppose my main questions are should I possibly look at beefing up the roof joists, just in case I decide to remove all of the side wall and use the new workshop wall to take the load of the joists or keep it simple and stick to my original plan?

When I do the flat roof should I leave the front of the garage as a wall with the coping stones and start the roof right after that kind of the way it is already? Or should I remove the coping stones and start my first joist there?

I thought I had lots of questions but can't remember anything else for now. Oh and the plan is to get one of the golfs inside at a time to finish them off but I own too much crap and garage is tiny hence wanting to gain some space and headroom so I can put shelfing up higher.

Oh I'm also getting a new roller shutter door fitted tomorrow so I can use the wall space at the front of the garage too.

Thanks for any advice or ideas to make this a reality.

 

[Notch7]

You might want to remove coping stones + 2 courses of bricks so the new flat roof ends up being no higher than existing - you don’t want a planning issue


the existing roof design with parapet walls is awful, it’s just asking to leak.

I recommend you use EPDM rather than felt - easier for a DIYer to do with out leaks

 

[bobbydigital]

Appreciate the advice on the wall height I should have mentioned I was going to remove at least one course of bricks as can be seen on one of the photos one of the bricks/coping stone was already loose and I took it down. I believe the max height is 2.5m as my garage is on the boundry.

I'll look into the EPDM I assumed it would be harder to fit.

 

[bobbydigital]

the existing roof design with parapet walls is awful, it’s just asking to leak.

Oh it sure is and the sheet material condensation is a nightmare too. Not to mention the wasted space, door end is 247cm height inside, rear is 199cm. I'd like to get full height so I can push a car right back and build storage either side and above.

 

[Notch7]

Appreciate the advice on the wall height I should have mentioned I was going to remove at least one course of bricks as can be seen on one of the photos one of the bricks/coping stone was already loose and I took it down. I believe the max height is 2.5m as my garage is on the boundry.

I'll look into the EPDM I assumed it would be harder to fit.

2.5m is correct, but I would’ve though you could go as high as existing if that’s more - somebody might be able to confirm.

by the way, be careful removing the 2 existing roof beams I would leave them in place until you are ready to fit the new joists - because without them you have 2 long and tall single skin walls.

EPDM is easy to fit, just watch the videos / instruction.I buy from rubber4roofs and they have lots of excellent guides.

If you want to extend the garage later and cut an opening between, then plan the lintel and put in place now ready. Don’t fit 4.8 joists unless you intend building straight away - just make the garage roof joists the length the need to be but make sure you leave access to slot in new joists.

don’t forget to fit straps to fit the joists to the brickwork - they are about a metre long so you get fixing in the broickwork well down from the top few courses

 

[bobbydigital]

Thanks again top advice.

I wasn't even going to remove the original sheets until I had built the new roof frame, so that when I'm ready to fit the OSB boards it reduces exposure of the garage internals to the weather.

I want to extend the garage asap to be fair, in an ideal world I would fit timbers that were capable of say 5m span but that's probably going to open up a whole new can of worms in the sense of building a load bearing wall to pick them up once I remove said wall. I feel more comfortable only removing parts of the wall and that is the load bearing and although the timber workshop/extension is attached it isn't doing the main load bearing.

The main thing holding me back about the workshop is I need to figure out what to do for foundation which means taking up some slabs to see what is under there but they are cemented down, so I think I should focus on one job at a time lol.

 

[bobbydigital]

Free UK Span Table for Flat Roof Joists to BS 5268-7.2 (C16, 1 kN/m² load) - Timber Beam Calculator

www.timberbeamcalculator.co.uk

This is the table I've been using to work out spans fyi.

 

[Ivor Windybottom]

Is it damp? It looks it from the photos, the front has lots of salt staining and the paint inside has fallen off the pointing.

As you're embarking on such a major overhaul, perhaps consider just flattening it and start again? Make it the size you actually want and include a cavity wall, which wouldn't be that much wider anyway due to the numerous pillars on the inside of the walls.

Obviously will cost more initially, but possibly not much more if you're talking about extending out anyway.

 

[bobbydigital]

Damp where it leaks, I wish I had the money to flatten it but also saving for a side extension for the house and not long done basically a complete other floor to house (attic conversion with dormer but the size of it is basically the same as the original downstairs).

Roof and wooden workshop I have the cash to do now.

Can't see too well in the photo but it basically leaks down the walls because of the state of the kerbs (if that's correct term).

 

[bobbydigital]

47 x 175 (44 x 170mm finished sizes) Eased Edge C16 Grade Timber Joists - Stoke Timber

C16 Graded Untreated Joists The Product 44 x 170mm mm joists available in 3.0m, 3.6m, 4.2m, 4.8m and 6.0m lengths. Also referred to as 7” by 2” joists available in 10ft, 12ft, 14ft, 16ft and 20ft lengths.* *Please note, finish sizes are Metric (milimetres and metres) and not Imperial (feet and...

stoketimber.com

Bottom two are C24 treated they seem good option for roof joists?

or should I go for https://stoketimber.com/product/75-x-150mm-x-4-8m-c24-treated/


Both seem to be fine for the span but just wondering if there is a benefit to either other than if I decide to insulate at some point.

 

[bobbydigital]

New question:

I was going to build the roof sloping the same direction (towards the shed, which will be replaced also eventually most likely lean-to structure on back of garage).

Garage is 503cm long most pre-made firrings are 4.8m long. I suppose I could add an angled cut would to the first roof joist to make up for this.

Or should I possibly rethink and have the roof slopped towards the garden, I could then set the angle of the new joists by using different sized wall plates or another method?

I honestly don't know the pros and cons of either method and would appreciate any advice

 

[Ivor Windybottom]

It's a single skin wall and probably doesn't have a damp proof membrane. You may be able to reduce the amount getting into the top, but it will always be damp.

It looks like there's plenty of damp in the bottom of the side wall, where it's painted on the outside.