Lean-to type vaulted ceiling/roof - how to construct one?

[Spacecowboy]

I'm about to embark on an extension project to the rear of my house - 2x4. The only part I have very little experience of is roofing and I want to create a vaulted ceiling look.

Can anyone give me an idea how this is best achieved? I plan on fitting french doors to the rear opening or even doors that open up the full length of the rear (concertina).

I'm concerned about wall spread. What is the best construction method to achieve the look? Any help or pointers much appreciated.

 

[^woody^]

By vaulted ceiling, do you mean a roof held up by arched timbers, or do you mean you just want the ceiling to be on the underside of the rafters and not a horizontal one?

 

[Spacecowboy]

Exactly right - the ceiling to be on the underside of the rafters rather than having a horizontal regular flat ceiling - this is a single storey.

If you can recommend a good roofing book to read that would be appreciated. WHat degree of pitch should i be looking for for example?

 

[noseall]

If it is a lean-to roof then spread isn't an issue as the abutted wall acts as restraint.

If it is a pitched roof then spread is countered using a steel ridge.

Insulating can be achieved using celotex or kingspan either by cold or warm deck construction.

The size of the patio doors may be governed by the glass-per-floor area and corner buttressing.

Pitch of the roof should fall within the range of the roof tile you decide to use, which in turn is selected to match existing. If height constraints limit the pitch of the roof then there are shallow pitch roof tiles available.

 

[Spacecowboy]

Thanks for the info its about what i expected.

In terms of pitch, I wish to match the existing roof therefore I will be governed by that and the tiles that are up there. Good point about the glass per floor level - I'd not considered that.

In terms of physical construction, are you able to advise what is needed or recommend a decent reference book to get me started? Last thing I want is a leaky roof or condensation build up because its not able to breath.

Oh, and what is cold/warm deck construction?!

 

[noseall]

Roof pitch and span will determine the size of timbers for the rafters.

By the sizes you have given and presuming you are spanning the shortest run (2m x 4m) i'd be surprised if 125mm x 50mm rafters at 400mm c/c didn't do the trick.

At the high end (vertical wall) these could be supported by a 125mm x 50mm pole plate (pitching plate), secured to the wall with expanding bolts. This is underslung beneath the rafters.

At the low end (top of internal wall) the rafters can be birds-mouthed onto a 75mm x 50mm tanalised wall plate.

Warm or cold deck roofs are defined by the position of the insulation relative to the rafter.

Warm deck is defined by the insulation sitting completely above the rafter and requires no venting.

Cold deck is when the insulation sits between and/or below the rafter and requires venting.

Venting can be achieved by using over-fascia vents and an abutment flashing vent system. Breathable membrane may be ok so long as you adhere strictly to other condensation preventing measures, i.e. foil backed plasterboards etc.

 

[^woody^]

The Building Construction Handbook by Chudley and Greeno is a good reference book for all things building. There is a not much specifically on mono-pitched roofs, just some basics, but there is more detail available in general terms from the other roof sections, which you can then apply to mono-pitched roofs.

Another good place will be the sites of the tile manufacturers - Redland (now Monier) and Marley (now Marley Eternit) who have roof details along with tiling and felting information

 

[Spacecowboy]

Noseall and Woody - many thanks that info is just what I'm looking for. I've been ldoing a bit of research recently so it makes a lot more sense now too.

Again, many thanks.