Advice on building a garden studio (terraced house)...

delmonta

Bendy_House said:

The roof doesn't have to slope down towards the back either. If space at the rear is a premium, then it can slope towards the front, with the guttering fitted at the end of the front 'canopy', and a fascia board added to disguise this from the front view. Ie, it'll look 'flat', not sloping. There's also 'box' guttering designed for concealed situations like this.

This will, of course, make cleaning out a blocked gutter a LOT easier...

Options! :-) 

Too many options! I think it will slope to the back just because it will look better in such a small garden, and if I have to leave a maintenance gap then the gutter is no issue. Even if I don't I'm sure there is still space for guttering

casper_gutman

delmonta said:

Bendy_House said:

If going EPDM roof - and I'm not trying to persuade you against it - please ensure the WHOLE roof design is correct, with no *unventilated* gaps, voids, or traps where condensation could form. 

Two basic types, 'warm' and 'cold'. Not sure about pros and cons, but it's things like overall thickness and stuff.

Sorry could you elaborate on this as I'm not sure I understand? 

With a "cold roof" the insulation goes under the boards (OSB, tongue and groove or whatever) forming the roof deck, so the roof structure itself is outside the insulation and therefore is physically cold. Because the boards are cold, condensation can form on them promoting rot. You therefore need a ventilated space between the insulation and the roof structure above.

The pitched roof of a typical British house works this way: the insulation is laid on the "floor" of the loft space, the entire space is a ventilated air space and the roof structure is above this.

You form a "warm roof" by laying boards for the roof deck over the joists then putting the insulation on top of this. The roof covering goes over the insulation. The deck is physically warm as it's inside the insulation, so condensation should be less of an issue.

delmonta

casper_gutman said:

delmonta said:

Bendy_House said:

If going EPDM roof - and I'm not trying to persuade you against it - please ensure the WHOLE roof design is correct, with no *unventilated* gaps, voids, or traps where condensation could form. 

Two basic types, 'warm' and 'cold'. Not sure about pros and cons, but it's things like overall thickness and stuff.

Sorry could you elaborate on this as I'm not sure I understand? 

With a "cold roof" the insulation goes under the boards (OSB, tongue and groove or whatever) forming the roof deck, so the roof structure itself is outside the insulation and therefore is physically cold. Because the boards are cold, condensation can form on them promoting rot. You therefore need a ventilated space between the insulation and the roof structure above.

The pitched roof of a typical British house works this way: the insulation is laid on the "floor" of the loft space, the entire space is a ventilated air space and the roof structure is above this.

You form a "warm roof" by laying boards for the roof deck over the joists then putting the insulation on top of this. The roof covering goes over the insulation. The deck is physically warm as it's inside the insulation, so condensation should be less of an issue.

Ok thanks for explaining, so what is most common when building these timber framed garden rooms? Or most appropriate perhaps

delmonta

Does anyone know if there are building regulations for foundations when building a garden room?

stuart45

delmonta said:

Does anyone know if there are building regulations for foundations when building a garden room?

Not normally, but if they do apply it's not just the foundations. The size you are building should be OK.

FreeBear

The only work that you should/need signed off is the electrics.

Bendy_House

delmonta said:

Bendy_House said:

The roof doesn't have to slope down towards the back either. If space at the rear is a premium, then it can slope towards the front, with the guttering fitted at the end of the front 'canopy', and a fascia board added to disguise this from the front view. Ie, it'll look 'flat', not sloping. There's also 'box' guttering designed for concealed situations like this.

This will, of course, make cleaning out a blocked gutter a LOT easier...

Options! :-) 

Too many options! I think it will slope to the back just because it will look better in such a small garden, and if I have to leave a maintenance gap then the gutter is no issue. Even if I don't I'm sure there is still space for guttering

Looking at the pic of your patio again, your outside area appears to be quite level? In which case, I agree that backwards-sloping would look better as all you'd have at the front is a slim neat fascia like on the example shown by Doozer.

Had the location of the room been on slightly higher ground, then it could have sloped towards the front as an alternative, and the fascia - possibly a bit taller - would have hidden any visible sloping roof behind it.

Bear in mind that you might - most likely will - need regular access to clear out the gutter, as it'll likely fill with leaves. So you'll need enough room to get 'up' there to do this.

If you go EPDM roof, then it'll obviously need to be fully supported by ply, OSB or similar, which means that this supporting sheeting will be 'sealed' on its outside. You need to ensure the roof design will not allow moisture from inside the room to perculate through and get trapped there. 

Google is your friend... 

delmonta

FreeBear said:

The only work that you should/need signed off is the electrics.

But its ok for me to do the electrics and just get the electrician to come and do the final fix?

delmonta

Bendy_House said:

delmonta said:

Bendy_House said:

The roof doesn't have to slope down towards the back either. If space at the rear is a premium, then it can slope towards the front, with the guttering fitted at the end of the front 'canopy', and a fascia board added to disguise this from the front view. Ie, it'll look 'flat', not sloping. There's also 'box' guttering designed for concealed situations like this.

This will, of course, make cleaning out a blocked gutter a LOT easier...

Options! :-) 

Too many options! I think it will slope to the back just because it will look better in such a small garden, and if I have to leave a maintenance gap then the gutter is no issue. Even if I don't I'm sure there is still space for guttering

Looking at the pic of your patio again, your outside area appears to be quite level? In which case, I agree that backwards-sloping would look better as all you'd have at the front is a slim neat fascia like on the example shown by Doozer.

Had the location of the room been on slightly higher ground, then it could have sloped towards the front as an alternative, and the fascia - possibly a bit taller - would have hidden any visible sloping roof behind it.

Bear in mind that you might - most likely will - need regular access to clear out the gutter, as it'll likely fill with leaves. So you'll need enough room to get 'up' there to do this.

If you go EPDM roof, then it'll obviously need to be fully supported by ply, OSB or similar, which means that this supporting sheeting will be 'sealed' on its outside. You need to ensure the roof design will not allow moisture from inside the room to perculate through and get trapped there. 

Google is your friend... 

Thanks, yeah tomorrow I'm going to clear the garden up and have a proper look. But I think I can leave 30cm around all sides and the room will still be a decent size. so I could get to the gutter from the back as there is a waist height brick wall to stand on. Or as you say get on the roof

So yes I need to give the roof some thought, especially with this window...as you and another poster mentioned condensation

casper_gutman

delmonta said:

...what is most common when building these timber framed garden rooms? Or most appropriate perhaps

Not sure which is most common. Maybe a warm roof is used more on new construction, but a cold roof is often used when retrofitting insulation to an existing building, because people just add the insulation from the inside. Too often this leads to condensation and damp because they neglect the need for a ventilated air gap.

My own log cabin has a pitched roof. I used a layer of celotex over the roof boards, then nailed right through it to attach roof shingles on top. This was an easy option a d gave an uninterrupted layer of insulation over the whole roof.

I have a slight niggling suspicion I should have included a breathable membrane somewhere in the roof make-up, but so far it's all okay three years in.