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Shed build - help

Lumen

I'm about to build a shed. I have no construction experience but I have a plan.

The basic design brief is:

- For non-habitable use, e.g. storage, hang out, home office.
- 4m ridge height.
- 15sqm internal floor area suspended.
- Ground screw foundation with topsoil replaced by gravel and land drain underneath.
- Structural ridge beam for completely open interior space.
- 40 degree slated roof

I'm going for ground screws as it's in a wooded area and I don't want to disturb tree roots. Plus no DPM/DPC required as water can't crawl up the posts.

The ridge beam is 4.8m x 225mm x 75mm x 3 and end posts are same. I've done my own calculations which I might run past a structural engineer, but I think it's OK (not posting details or asking for advice here on that as I think it's against the charter).

I'm planning on putting the racking on the outside of the studs beneath the insulation as it gives better continuity and leaves me to mess around in the studs without compromising wall performance.

Wall build up is (from inside):
- Stud 100mm x 44mm, open
- Racking 15mm ESB (OSB)
- Insulation 80mm Gutex
- Membrane (Pro clima SOLITEX FRONTA WA?)
- Vertical batten 22mm
- Horizontal counter-batten 22mm
- Cladding 18mm vertical larch

Roof build up is (from inside):
- Rafter 150mm
- Racking 15mm ESB (OSB)
- Insulation 80mm Gutex
- Membrane?
- Vertical batten 22mm
- Horizontal counter-batten 22mm
- Tiles 5.5mm natural slate

Floor build up (from ground)
- Sub-floor 175mm x 44mm, doubled on outer members held by ground screws
- Membrane over joists?
- Insulation 100mm Gutex
- 22mm ESB (OSB).

I have a load of questions about fasteners, roofing etc but for now, opinions on the general approach and build up would be much appreciated.

I think the only place I have cold bridging is in the subfloor. Maybe 80mm woodfibre is a bit stingy there? Or I could maybe use thinner joists (150mm) with another cross member and drop in 25mm of under-OSB insulation?

Haven't figured out gutters and window/door details yet.

I'm not entirely sure about the membranes either.

Anyway, does this all look OK?

It's a bit of a brain dump so I've bolded the questions.

Pics of each layer:
https://imgur.com/a/Wv51TjD

Animated gif:
https://i.imgur.com/mIVnQUX.gif

Quantities (BOM ?)

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Comments

Rows Grower

I want an invite to the shed warming party.

mloc123

Any updates?

FrancieBrady

mloc123 wrote: »

Any updates?

Give the man time, will ya! You can't rashly choose any old hinges you know. These things take time

uck51js9zml2yt

FrancieBrady wrote: »

Give the man time, will ya! You can't rashly choose any old hinges you know. These things take time

He's only had 7 months!!

Rows Grower

Rows Grower wrote: »

Lumen, what's the story?

Getting worried about no new updates this last while.

C'mon Lumen, keep us in the picture.

This was posted over three months ago, just saying.

Lumen

I'm doing bugger all at the moment because it's cold and dark and my wife keeps giving out about all the other stuff I haven't finished.

Rows growing, one might say :pac:

Rows Grower

Lumen wrote: »

I'm doing bugger all at the moment because it's cold and dark and my wife keeps giving out about all the other stuff I haven't finished.

Rows growing, one might say :pac:

It's getting brighter earlier and the days are starting to get longer Lumen, I'll be expecting some progress when the weather improves.

This may well end up as your new abode the way things are going.

mloc123

Tick... Tock.

Lumen

Right then. Having spent the spring getting the garden back into shape/avoiding the shed, I finally got back to it today.

Brushed off all the winter debris.
Finished carving the ridge insulation (this was hard).
Laid membrane over the ridge to help it shed water in the event of a shingles failure.
Cut the first set of roof battens, connected and positioned loosely with tape.

Next job: try and throw some 220mm screws through the battens, insulation, and OSB to hit the 44mm wide rafters. My inside out design, accumulated measurement errors and obsession with air tightness makes this rather like playing darts blindfolded....

I also need to revisit sketches of gutters and roof shingles, so I can work out correct batten length for a flush eaves detail.

And get a new phone, cos after smashing the lens cover on my current ones the pics are splodgy.

Oh, and no, it still doesn't have a door. Or windows. :pac:

Anyway, the motivation is back!

Lumen

If anyone has anything insightful to say about guttering now would be a great time.

I'm thinking of running two half-round gutters along the sides, collecting into one downspout at the back, into a 100mm pipe which will take the water a couple of metres clear of the downhill end of the shed, and then out into the hedgerow. Reason being to keep water away from the ground screws.

Don't want PVC as there's no plastic in the build (apart from the membranes), and am looking at the Lindab Rainline galvanized steel system.

https://nationwidegutters.ie/wp-content/uploads/2017/05/Galvanised_Steel_drainage_systems.pdf

Only issue is that it all seems to be painted but I'd quite like naked metal.

Obviously being an idiot I'm considering copper too.

my3cents

Neighbor has a zinc gutter system. Its rubbish but he wanted it because they are by the sea and the less than 10 year old aluminium guttering was already on its way out from corrosion. I think its not as good as it could be as the fittings are very basic, I suspect the builder got a cheap agricultural guttering system instead of a domestic one. I don't think zinc is a bad idea just this particular system should have gone on a barn not a house.

hesker

Why no pvc?

Have you thought of a soakaway. You can buy modular crate systems that are very easy to build.

Lumen

hesker wrote: »

Why no pvc?

Have you thought of a soakaway. You can buy modular crate systems that are very easy to build.

I've made quite a bit of effort to avoid plastic in this build and since I only need about 14m of guttering (and a downspout) it seemed reasonable to push the boat out.

Don't think I need a soakaway as it's sitting above about 30m of a 10% slope with trees and hedging.

Lumen

my3cents wrote: »

Neighbor has a zinc gutter system. Its rubbish but he wanted it because they are by the sea and the less than 10 year old aluminium guttering was already on its way out from corrosion. I think its not as good as it could be as the fittings are very basic, I suspect the builder got a cheap agricultural guttering system instead of a domestic one. I don't think zinc is a bad idea just this particular system should have gone on a barn not a house.

edit: I'm 2.5km from the east coast but about 100m up and sheltered so salt isn't much of an issue as far as I can tell.

Reading a few reviews of Lindab with people saying they get corrosion from the uncoated galvanized system, which is maybe why the supplier I was looking at only supplies it painted.

Zambelli get better reviews and it's German so it has to be good, right?

http://www.qbm.ie/rainwater-systems/

(I have to replace the gutters on my house soonish so that's the other reason for getting decent stuff, as a trial run)

Bullocks

Lumen wrote: »

edit: I'm 2.5km from the east coast but about 100m up and sheltered so salt isn't much of an issue as far as I can tell.

Reading a few reviews of Lindab with people saying they get corrosion from the uncoated galvanized system, which is maybe why the supplier I was looking at only supplies it painted.

Zambelli get better reviews and it's German so it has to be good, right?

http://www.qbm.ie/rainwater-systems/

(I have to replace the gutters on my house soonish so that's the other reason for getting decent stuff, as a trial run)

I think skillbuilder on youtube has a lindab video up (could be Robin Clevette either ). Looks like really good stuff from that video . I'd love to see the price of it for a house

Lumen

Finally finished with membranes and battening, at least for this pre-windows phase, apart from the odd corner.

To align the roof battens (so that I could hit the rafters through the 100mm of insulation + OSB with the 220mm Spax screws) I poked a kebab skewer up next to a rafter and out past the insulation, and then offset the others based on laser measurements from the rafters inside.

I was going to leave the wood fibre roof insulation open to the elements (as it's impregnated with paraffin wax so will cope fine in theory) but because I'm going for a design with no overhangs, soffits or fascia board I thought it safer to complete the wrap in case any rain gets driven up past the guttering.

At this stage this project feels like about half upholstery.

Cedar shingles arrived last week. At about €40/sqm they're not much cheaper than slate, and won't last as long, and the structure was designed to take a full slate roof load, but....I reckon the shingles will be more in keeping with the overall aesthetic, and they'll age consistently with the larch cladding. This is aesthetically a shed, even if it's designed to perform like a habitable building.

I might even go for shingles on the walls, like this house currently under construction somewhere on this island.

You can see the effects of rain splash at the bottom of the walls. It should all wash off but can't be doing the membrane much good. That's why I want to get the roof and guttering sorted ASAP....

(click thumbnails for larger images)

GreeBo

Look who's back!

Are you going to gravel/etc around the base of the shed? That splash is going to splash all over your shingle wall, even with a gutter since you have no overhang.

Did you have to remove any residents from under the shed?

BarryD2

Likely not very helpful, but you'd have made life a whole lot simpler by just pouring a 6 inch reinforced concrete slab to build off..

Lumen

BarryD2 wrote: »

Likely not very helpful, but you'd have made life a whole lot simpler by just pouring a 6 inch reinforced concrete slab to build off..

Not that simple on a 10% slope with tree roots all over the place. I'd have either had to cut down the tree and level the whole area, or use concrete pile foundations, neither of which appealed.

At the beginning of the project the faffing with misaligned ground screws seemed like a big time suck, but that was back when I thought I could finish the whole thing in three weeks.

Lumen

GreeBo wrote: »

Did you have to remove any residents from under the shed?

Nope, and the mesh is still sitting in my basement. I haven't done a full inspection yet. Maybe I'll send the terriers under there....

GreeBo wrote: »

Are you going to gravel/etc around the base of the shed? That splash is going to splash all over your shingle wall, even with a gutter since you have no overhang.

It's a bit of a worry. I might use bark mulch as I reckon there'd be less splash off it than gravel.

Relatedly, I buried 20m of 6 inch permeable pipe along the hedge line to take the run off from the roof, so that's my irrigation sorted.

Bullocks

Do you have to counter batten to nail the shingles to ?
When the gutters are on I'd say there will be frig all splash back and even any splashback won't be too noticeable if it's onto something clean as opposed to clay / dirt .
I think barkmuch will be a bit woody alongside the full thing clad in shingles aswell but thats just a personal preference and might be exactly what you like

Lumen

Bullocks wrote: »

Do you have to counter batten to nail the shingles to ?

Yeah, the same 50 x 35mm I've used to hold on the insulation. The nails are 31mm stainless ringshank from inox.ie (finally I've found a supplier of stainless fixings in Ireland!). I think I need 18 battens on each 5.something metre slope, so that's 45 x 4.8 cut in about three different ways according to my spreadsheet.

Bullocks wrote: »

When the gutters are on I'd say there will be frig all splash back and even any splashback won't be too noticeable if it's onto something clean as opposed to clay / dirt .
I think barkmuch will be a bit woody alongside the full thing clad in shingles aswell but thats just a personal preference and might be exactly what you like

I'll probably leave the cladding for a while anyway, as I've windows to think about. Once the gutters are on I can monitor the splash for a couple of months and make a decision. It's quite dark under the tree anyway, I might just plant some shade-loving ground cover plants or mossy rocks or something. But some clean dark-ish pebble might be a nice contrast....

Lumen

Shingling in the rain today.

Lumen

So, shingles took pretty much the whole bank holiday weekend, and I've still about 20% of one side remaining (I ran out of stainless steel ringshank nails).

Then we had a couple of days of heavy-ish rainfall with little wind, so I have a chance to examine the rain shedding performance.

It's....not perfect. Despite correctly overlapping the shingles and using a double layer at the drip edge, it seems that the water is crawling back under the drip edge and in places wetting the bottom two sets of counterbattens. The counterbattens further up are dry as a bone.

I could have prevented this by using a strip of membrane over the bottom two counterbattens, but since the main roof structure itself is well protected under a layer of continuous lapped membrane (and the insulation under the membrane is water resistant), I wasn't really fussed about the counterbattens. So I guess the question is whether a treated counterbatten subjected to period indirect wetting is going to rot. I guess I'll find out...

Although I guess I can poke a thin strip under the bottom batten to give that some protection, since they're nailed further up.

GreeBo

Lumen wrote: »

So, shingles took pretty much the whole bank holiday weekend, and I've still about 20% of one side remaining (I ran out of stainless steel ringshank nails).

Then we had a couple of days of heavy-ish rainfall with little wind, so I have a chance to examine the rain shedding performance.

It's....not perfect. Despite correctly overlapping the shingles and using a double layer at the drip edge, it seems that the water is crawling back under the drip edge and in places wetting the bottom two sets of counterbattens. The counterbattens further up are dry as a bone.

I could have prevented this by using a strip of membrane over the bottom two counterbattens, but since the main roof structure itself is well protected under a layer of continuous lapped membrane (and the insulation under the membrane is water resistant), I wasn't really fussed about the counterbattens. So I guess the question is whether a treated counterbatten subjected to period indirect wetting is going to rot. I guess I'll find out...

Although I guess I can poke a thin strip under the bottom batten to give that some protection, since they're nailed further up.

Looks well, like an old tiled roof.

How deep is the overhang?
Looks like 2" or so?

The first set of battens is probably ok...the second set would concern me...how much drying is it actually going to get?

listermint

Personally id probable just go get some dry drip edge. It comes in about 2.1 Mtr lengths various colours. and just slot it under the first run of tiles. Youve gone to the trouble elsewhere. Best not lead the leading edge as exposed as it is.

Lumen

listermint wrote: »

Personally id probable just go get some dry drip edge

Thanks. Got a link?

Lumen

Actually, maybe I just need a thin flat metal profile in between the two bottom shingles.

Where would I get that?

Edit: or this?

https://www.lenehans.ie/raw-aluminium-unequal-corner-profile-10mm-x-40mm-x-1m.html

Lumen

I picked up some cheap expanded metal mini-mesh and will do some experiments...

GreeBo

listermint wrote: »

Personally id probable just go get some dry drip edge. It comes in about 2.1 Mtr lengths various colours. and just slot it under the first run of tiles. Youve gone to the trouble elsewhere. Best not lead the leading edge as exposed as it is.

Is it a drip though?
It looks more like a bleed through to me?

Though maybe heavy rain & wind would explain it.

No harm to try the drip strip though!