Newbie Man Cave build- questions

[Mecha GG]

Hi everyone, first post!

My second child arrived recently and my wife has suggested that the 3rd bedroom could be put to better use for him- meaning my Man Cave's days are numbered. So in exploring my options I stumbled upon the idea of building an outdoor office. There are loads of websites in the UK who sell these, but they all either look flimsy, or look way overpriced.

I'm looking for the office to be around 3.5m x 2.5m, so about the size of a normal room. It would also need to have power and be well insulated. The diagrams in the stickied "Build a Shed Mike's Way" are excellent for a noob like me, but I had a few more questions.

1) The base. I originally liked the idea of a concrete base, as my site could be easily accessed by a mixer truck and poured in. Is this the best option for a workshop with power fed into it? Could I get away with a Shed Pier Foundation?

2) Framework: Seeing as it's a small workshop/office I don't want to "over-engineer" it. Would I still need 100 x 50mm studs for the framework or could I go smaller?

3) Insulation: The insulation wool seems to be sold in 600mm width. Should I make this the distance between studs?

4) Software: Is there a nice free 3D drawing program for doing a mockup of my shed? I tried a little bit with Google Sketchup, but it is quite simplistic and easy to mess up.

5) Roof: I'm planning a pent roof, but are there any advantages to doing a normal apex one?

Thanks in advance!

 

[Fitzroy]

I'll throw my twopence in.

1. My pal dug out and laid a concrete slab, i did pier foundations and made a framed base. Both were graft, neither is an easy option if you want a quality base. IMO biggest advantage to the concrete base is that it's close to ground level, my base is 20cm off the ground so my overall build is higher. If you're aiming to keep it under 2.5m, to allow it to fall inside permitted development rights, i think you'll need to do a concrete base.

2. I've built in 100x50 studs and the resulting structure is bomb proof, but does feel somewhat over engineered. One consideration would be if you are planning to insulate, if you go smaller than 100mm you will have to use kinsgpan/celotex to get any reasonable insulation, which is more expensive than glass wool batts.

3. 600mm is a standard spacing for studs.

4. Best free 3D drawing program is Sketchup. It's pretty powerful but advise you look on youtube for some tutorials to set you off on the right path.

5. I went for a pent roof, a 3m wide span needs 150x50mm beams to make the span at 600mm centres. With 18mm OSB on top this feels ok to walk on. An apex roof can be made from lighter section timber but you have to build the trusses, for a pent roof all you have to cut is the birdsmouth on each beam.

I think with an Apex roof you will get more usable space for a maximum roof height. An Apex will give low ceilings at the eves but max height in the middle (where you'll likely spend most time standing), where as to get the same height in the centre of the space with a pent roof the roof will have to be heigher at the 'flying' edge, if you see what i mean.

Fitz.

PS. My biggest learning has been that most jobs take longer than planned and with kids about (I have two under fives) expect progress to be slow.

 

[Mecha GG]

Many thanks Fitzroy. Tell me about it, I also have two under fives. Luckily the wife is taking them both to visit in-laws in Spain next month, so rather than just getting drunk for 7 days straight I thought I should make a start on the project!

I guess it's better to be over-engineered than under-engineered. Hadn't thought about roof beams needing to be thicker. Would the floor beams need to be 150 x 50 too? And actually just thinking about that:

6) I've seen people cutting out parts of the roof beams in pent roofs so that they sit nice and flush on top of walls. Does anybody have a link to a good set of instructions on how to do this accurately? My freehand sawing is horrendous.

 

[Fitzroy]

Regarding the floor it depends on your pier spacing, joist span and joist spacing. http://www.home-extension.co.uk/tech2.html shows you the recommended max spans for different floor joists.

The base on my build (6mx3m-pent-workshop-build-t97540.html) has 150x45 joists on 400mm centres and the base is 3m across so i'm right on the max span width. However i have piers at the centre of every third joist and the joists are all connected with noggins at both ends. With 18mm OSB as the floor it all feels OK.

6. I found the easiest way to cut the 'birdsmouths' was to mark them out with a strong knife-line, then cut the back cut with a saw, cut most of the waste out again with a saw and pare down to the knife-line using a plane iron as a wide chisel. With a pent shed roof the angle of the roof will likely be very shallow (10°ish) and the birdsmouth will mirror this angle so using any mechanical approach to cutting them out will be difficult.

PS. The plane iron is kind of a poor man's slick/framing chisel (which I would have loved to buy but couldn't justify for one job).
PPS. I have found the easiest way to correct my horrendous freehand sawing is to swap to a Japanese pull saw, the Ryoba double edged one (rip one side cross cut the other) has been priceless during my build.

 

[whiskywill]

Tell me about it, I also have two under fives.

(I have two under fives) expect progress to be slow.

Wimps. :wink: I have two three year olds and one at 10 months old and I get at least an hour free in my workshop, every week, to do whatever I want.

 

[Stanleymonkey]

My second child arrived recently and my wife has suggested that the 3rd bedroom could be put to better use for him- meaning my Man Cave's days are numbered.

Been down this route when son arrived.....

Yesterday my wife suggested that kids could now share a room and SHE could have the third bedroom as her office!

You have been warned

 

[Steve Maskery]

My 2p
You don't need floor joists at all.
Lay a concrete base.
After it has cured, cover it with a damp-proof membrane.
Lay 50mm polystyrene.
Cover that with 18mm OSB (actually, with a room that size you could probably skip this layer)
Cover that with Cabershield.
Fantastic floor.

Other bits:
100x50 is not too big, nor is it expensive. What will you gain by going smaller? A few quid for the sake of compromising your structure? And you'll have less scope for insulation.
If you are laying services to your man-cave, such as electricity, consider also water and wi-fi at the same time. It's not much extra work and considerably extra luxury.
Bear in mind that Plywood and OSB is widely available as 8' x 4' but plasterboard is 2.4 x 1.2m. They are not the same.
There are 137 pages here if you have a minute...
Clicky

 

[Shultzy]

I agree with Steve's shed building tips but i went for a wooden floor with 100mm insulation on bricks on 600mm x 600mm paving slabs. You need to plan the shed in great detail and make adjustments for wood/sheet sizes to save on waste. I have a pent roof but I made sloping trusses. My shed build is a modest 7 pages but you might find a few tips.

PS. If you want a sketchup copy of the framework of my shed, let me know, and I can adjust it to your sizes.

 

[MattRoberts]

Hands up who's thought about buying a little tiny dust mask, ear defenders and safety glasses so the little one can come in the workshop while you get stuff done?!