Dom's workshop build

[MikeG.]

You can put Celotex underneath the slab, or you can put it above it. I don't have either, and my workshop is plenty warm enough with a small electric heater, which isn't on all the time I'm out there in winter.

The junction between an internal wall and an external wall is easy. Build the external wall first, complete with OSB, then build the internal wall inside it. You need extra noggins in the external wall placed to enable the internal wall to be fixed through to it.

BTW, I suggest 3 course of bricks, so that you can have a skin of 50mm blockwork inside the plinth. Not only is this a little extra insulation, but more importantly, it enables the outer cladding to meet the plinth properly, without a 60mm gap/ overhang.

 

[DomD]

Thanks for the advice on the insulation and internal wall.

BTW, I suggest 3 course of bricks, so that you can have a skin of 50mm blockwork inside the plinth. Not only is this a little extra insulation, but more importantly, it enables the outer cladding to meet the plinth properly, without a 60mm gap/ overhang.

I saw this in your build and agree it seems like a good idea: does using this method mean you also do not have to cast the metal straps into the concrete but can instead wrap them under the blockwork? Anther point on bricks: what type should be used? Engineering? Facing?

Thanks

 

[MikeG.]

Yeah, casting them into the slab is wishful thinking really, especially on an amateur DIY build. Screw them to the face of the blocks. Bricks can pretty much be anything you like the look of. There is absolutely no need for engineering bricks.

 

[DomD]

I have started work on the CAD model: the walls (no windows yet) and roof are in (not the joists yet).

The roof is at 30 degrees, are there standards or better looking angles I should stick to?

All of the walls use 610mm spacing optimised for as little wastage of internal sheathing (rather than the usual external, meaning the offsets are non-standard) which means the gable end studs and rafters don't line up but I have read this is fine as I have a double top plate; is that correct? A side view for demonstration:

After looking into lots of wall construction techniques I have found lots have exterior sheathing - why is this not required for a build like this?

At the moment I have 650mm overhang at the front and back and 300mm gable overhang: I would like more at the front and back but will need to see if they fit.

The birdsmouth currently has a heel of ~42mm and a seat of 72.5mm shown here:

Hopefully that all looks okay: I am on to the joists tomorrow.

Thanks

 

[DomD]

I was thinking I could maybe do something like this where the red area has a high ceiling (with raised rafter ties) with no storage above it and the green area has standard roof joists resting on the double top plate:

The walls already mean the minimim roof height would be 2400mm+ so the lower roof in the electronics/enterance area wouldn't be a problem. This way the workshop area would feel more open and the storage above the other area could be easily accessed. How high can raised rafter ties be above the top plate?

As I was doing the gable ends I realised they were not in full contant with the rafters above - is there a proper way to fix this?

Thanks, Dom

 

[Peterm1000]

Dom,
My workshop is 14 foot square. I cannot imagine sub-dividing that as it is already pretty small. I have a table saw, mitre saw station, planer thicknesser, sanding station, pillar drill, bandsaw and workbench. My extractor is in a mini shed that backs onto the workshop. The two main recommendations I would make are:

1. Put EVERYTHING on wheels so you can fiddle about with the layout / change things as you change tools.
2. Put up battens on every wall at even distances for a French cleat system. I have most of my tools on the walls and again, French cleats give the most flexibility.

Good luck!

 

[MikeG.]

........ How high can raised rafter ties be above the top plate?....Thanks, Dom

This is a rule of thumb answer only, but in the bottom third of the rafter length. They can of course be anywhere on the rafter, with a declining influence on the spreading forces on the walls the further up the rafter they go, but I wouldn't advocate anything over a third of the way up the rafters without a structural engineer's say-so.

 

[MikeG.]

......As I was doing the gable ends I realised they were not in full contant with the rafters above - is there a proper way to fix this?

Halving joint. It's unimportant, though. They're only there to fix OSB to.

 

[DomD]

Dom,
My workshop is 14 foot square. I cannot imagine sub-dividing that as it is already pretty small. I have a table saw, mitre saw station, planer thicknesser, sanding station, pillar drill, bandsaw and workbench. My extractor is in a mini shed that backs onto the workshop. The two main recommendations I would make are:

1. Put EVERYTHING on wheels so you can fiddle about with the layout / change things as you change tools.
2. Put up battens on every wall at even distances for a French cleat system. I have most of my tools on the walls and again, French cleats give the most flexibility.

Good luck!

Unfortunately, I have to have somewhere to store my electronics so the subdivider is necessary, I am planning at the moment to do some sort of permanent mitre station/workbench with multiple wheeled tools such as the planer thicknesser and table saw underneath. The french cleats are a great idea, definitely a better solution than just nailing holders into the wall.

This is a rule of thumb answer only, but in the bottom third of the rafter length. They can of course be anywhere on the rafter, with a declining influence on the spreading forces on the walls the further up the rafter they go, but I wouldn't advocate anything over a third of the way up the rafters without a structural engineer's say-so.

And I suppose a structural ridge like this would be straying into structural engineer's territory too?

If so I guess I will just have a slightly higher roof in the main room than the electronics area (1/3 up).

Looking at Dan's Shed over on thewoodhaven2 I noticed he braced his walls before the cladding went on - is this recommended or does it just provide a little extra stability?
Finally, I have seen that a surrounding ditch of shingle is recommended for drainage: how deep should this be and does anything need to be under it or can it just drain into the soil?

Thanks all,
Dom

 

[DomD]

Another small question: if I plan to put tiles (not decided which) on the roof should there be a layer of OSB below the battens? If so I assume the roofing structure should be: tiles -> battens -> membrane -> OSB -> joists and insulation -> interior OSB/ply (vapour barrier).

 

[MikeG.]

No. Any OSB up there is just as a substrate for stuff such as EPDM or felt which needs it. If it is a tiled roof, or slate, then it would just be done in the conventional way with battens and membrane on the rafters.

 

[AJB Temple]

My thoughts. Don't be afraid of doing the concrete yourself. It is dead easy. All you need us framing boards around the edge and some pegs for levelling. You can make a tamper out of a scaffold plank and you should hire or borrow a poled float.

Pumped concrete is surprisingly hard work. I just did a 10 metre by 8 metre barn and an adjacent 5 metre by 9 metre slab at my place and we pumped that because most of it was internal. I think we pumped around 20 cubic meters and this was down, tamped and floated by 2pm having started around 9am. My wife and son helped. You will definitely need a mate to help. Will save you a lot to hire a digger, small dumper, put your own stone in reinforce as needed and lay.

As for size: my home workshop is an old pigeon loft and the main area is about 10m by 3m with a small store room as well at one end. It is hopeless for dealing with sheet goods. Plenty of head height is also good when you are moving big bits of timber around.

If your electronics area is going to house an oscilloscope or other sensitive kit, then I would without doubt make your shop L shape and seal the electronics room off with a door.

Check with your electrician what size armoured you need. Many people cut corners here and down spec with 4mm or something. Overspec it. When the day comes that you beed a 16amp bandaw, or P/T, plus extraction, a 3kw fan heater, lots of lighting etc you will be glad you did this.

Plan in an internet security camera and alarm. I always put in flexible trunking(50mm I think) as it is extra useful when you realise you need another cable. Always leave a draw cord in. And I would stick an ethernet cable through there as well. Plan to have a consumer unit in the shop, with its own trip switches. Costs peanuts, saves a lot of bother and adds flexibility.

When you are doing the trench for the armoured, stick a plastic water pipe in as well. Tap in or just outside workshop is very handy.

Work out how many sockets you think you need then double it. Then add a few more.

Bare concrete for a workshop floor is not good. It's dusty, wears, is hard on the feet. At the very least paint it before you start fit out. You will end up with rubber mats or something if you stand a lot.

Good luck.

 

[screwpainting]

+1 to all that.

 

[DomD]

My thoughts. Don't be afraid of doing the concrete yourself. It is dead easy. All you need us framing boards around the edge and some pegs for levelling. You can make a tamper out of a scaffold plank and you should hire or borrow a poled float.

Pumped concrete is surprisingly hard work. I just did a 10 metre by 8 metre barn and an adjacent 5 metre by 9 metre slab at my place and we pumped that because most of it was internal. I think we pumped around 20 cubic meters and this was down, tamped and floated by 2pm having started around 9am. My wife and son helped. You will definitely need a mate to help. Will save you a lot to hire a digger, small dumper, put your own stone in reinforce as needed and lay.

A digger probably won't be possible just due to the accessibility of the site; I can stretch the digging out over a long period however.
The levelling is the thing I am most worried about having never done it before and I may look around for quotes and see what it will cost and if it is worth it. Speed is also limited for this build (I have around 6weeks with lots of time to put in) so it might be better to get the slab laid as a time saver.

As for size: my home workshop is an old pigeon loft and the main area is about 10m by 3m with a small store room as well at one end. It is hopeless for dealing with sheet goods. Plenty of head height is also good when you are moving big bits of timber around.

If your electronics area is going to house an oscilloscope or other sensitive kit, then I would without doubt make your shop L shape and seal the electronics room off with a door.

Yeah, hopefully I should be able to have a open roof in the main area for moving around larger items. The separate room will definitely be a thing, though currently if you look at my plans you can see it is still a rectangle just with the sub room inside. Maybe an 'L' is a better use of space and I will experiment with a floorplan, though it does add extra complexity for the framing.

Check with your electrician what size armoured you need. Many people cut corners here and down spec with 4mm or something. Overspec it. When the day comes that you beed a 16amp bandaw, or P/T, plus extraction, a 3kw fan heater, lots of lighting etc you will be glad you did this.

Plan in an internet security camera and alarm. I always put in flexible trunking(50mm I think) as it is extra useful when you realise you need another cable. Always leave a draw cord in. And I would stick an ethernet cable through there as well. Plan to have a consumer unit in the shop, with its own trip switches. Costs peanuts, saves a lot of bother and adds flexibility.

Currently, the max I can get is 230v, 32A as my house main supply is only ~100A; I will talk to him about overspeccing but it is unlikely I will upgrade the main house supply. Hopefully with low power lights and using one tool at a time (with extraction) I should keep it below that. I plan to have a consumer unit.
I am definitely laying an ethernet cable and CCTV is a good idea as I already have a system set up.

When you are doing the trench for the armoured, stick a plastic water pipe in as well. Tap in or just outside workshop is very handy.

I will look into this but the building is above second floor height so the pressure might not be high enough to get it all the way up the hill: it would be nice to be able to make tea up there!

Bare concrete for a workshop floor is not good. It's dusty, wears, is hard on the feet. At the very least paint it before you start fit out. You will end up with rubber mats or something if you stand a lot.

I have seen people using self-levelling compounds - perhaps this is a possibility for the interior, will need to look into that. I suppose you can install the doors and everything first then pour a layer of it on the concrete only in the interior?

Thanks for all your input,
Dom

 

[MikeG.]

A power float finish on concrete is perfectly good for a workshop, and entirely dust-free. It's what I did in mine. The only downside is that it can be a little to smooth, and you sometimes don't get enough grip with your feet if you're planing something putting up some resistance. It can of course be painted.

 

[TopCat 32]

A power float finish on concrete is perfectly good for a workshop, and entirely dust-free. It's what I did in mine. The only downside is that it can be a little to smooth, and you sometimes don't get enough grip with your feet if you're planing something putting up some resistance. It can of course be painted.

Make sure when you order concrete you order the right slump, AJB quotes that a finished concrete floor gets dusty, not sure if he means cement dust dusty, and if he does this is because people order a S2 (70 slump) ,and when truck gets there wet it up to about a S3 reducing the strength and causing bleed which leads to the surface dusting up, they seem to do this as a S3 (130 slump) is obviously easier to lay as it is runnier but more expensive as it contains more cement to get it up to the scheduled strength, you will be surprised how many DIY ers come back to us a few days after laying moaning there concrete floor for there Garage/ shed is dusty, when we check 99.9% of the tickets have had water added at customers request, rendering guarantee null and void, experienced and well known groundworking companies do it all the time as well for footings and oversites, but as they are not going to be living in them i guess they dont care

Good luck

 

[DomD]

A power float finish on concrete is perfectly good for a workshop, and entirely dust-free. It's what I did in mine. The only downside is that it can be a little to smooth, and you sometimes don't get enough grip with your feet if you're planing something putting up some resistance. It can of course be painted.

Make sure when you order concrete you order the right slump, AJB quotes that a finished concrete floor gets dusty, not sure if he means cement dust dusty, and if he does this is because people order a S2 (70 slump) ,and when truck gets there wet it up to about a S3 reducing the strength and causing bleed which leads to the surface dusting up, they seem to do this as a S3 (130 slump) is obviously easier to lay as it is runnier but more expensive as it contains more cement to get it up to the scheduled strength, you will be surprised how many DIY ers come back to us a few days after laying moaning there concrete floor for there Garage/ shed is dusty, when we check 99.9% of the tickets have had water added at customers request, rendering guarantee null and void, experienced and well known groundworking companies do it all the time as well for footings and oversites, but as they are not going to be living in them i guess they dont care

Good luck

I will make sure to either use or specify S2; sounds like concrete on its own should be fine then.

I was experimenting with an 'L' layout shown below:

Its very hard to get a sense of scale but in this the electronics room does seem a bit small. It will also complicate the framing but could work better for space, especially in the central area. Does anyone have layouts/images of a shop about this size (16*13 exluding walls) so I could gauge the scale of it when done?

I will need to add furniture etc in CAD to get a true sense of size.

Thanks

 

[MikeG.]

It's not the framing that would complicate, it's the roof.

 

[DomD]

It's not the framing that would complicate, it's the roof.

Yeah, especially the joint between the two gables I imagine. Not really sure if it is worth it as it's also another part to square up etc.

This is my planned floor so far:

Dom

 

[MikeG.]

Don't fall into the trap of assuming depths of hardcore and blinding until you have actually dug a hole. It might be you don't need any hardcore, and if you don't, you'll only need a dusting of sand blinding.