Lean To Roof Extension Advice

nathanw · Posted: Mon Oct 19, 2009 9:51 pm Post Subject: Lean To Roof Extension Advice

Hi first post on here so please go easy on me !!

I'm proposing to add a single storey extension to my house.
I want to add a lean to roof with vaulted ceiling with Velux rooflights.
The extension will be approx 6m wide x 4m out and want the whole 6m width to be glazed.
Will I need anything out of the ordinary structurally with a 4m lean to span onto the glazing ?
Also would I need to ventilate the roof space as I'm a bit puzzled on this part with wanting to vault the ceiling ?

Thanks in advance.

noseall · Posted: Tue Oct 20, 2009 4:39 pm Post Subject:

I think your idea is bonkers.

Why do you want roof-lights in a glass roof?

The heat loss issues alone will be prohibitive let alone the design for the rafters/glazed roof.

freddymercurystwin · Posted: Tue Oct 20, 2009 5:22 pm Post Subject:

noseall wrote:

I think your idea is bonkers.

Why do you want roof-lights in a glass roof?

I think he means to do the rear wall in glazing not the roof.

To the OP you'll need a steel beam to span that opening something like a 305 or 254 deep UB. No need to vent the roof if its a warm roof.

HaydnExport · Posted: Tue Oct 20, 2009 7:54 pm Post Subject:

What freddy said, I was thinking the same as noseall until i re-read it.

nathanw · Posted: Tue Oct 20, 2009 10:07 pm Post Subject:

noseall wrote:

I think your idea is bonkers.

Why do you want roof-lights in a glass roof?

The heat loss issues alone will be prohibitive let alone the design for the rafters/glazed roof.

No roof will be tiled not glazed.
Do you really think I would want rooflights in a glazed roof.

Quote:

Also would I need to ventilate the roof space as I'm a bit puzzled on this part with wanting to vault the ceiling ?

Did this not give it away slightly ?

freddymercurystwin · Posted: Tue Oct 20, 2009 10:46 pm Post Subject:

To be fair, your post was poorly written!

btw You're welcome!

noseall · Posted: Wed Oct 21, 2009 5:05 pm Post Subject:

nathanw wrote:

Quote:

Also would I need to ventilate the roof space as I'm a bit puzzled on this part with wanting to vault the ceiling ?

Did this not give it away slightly ?

AYE!

nathanw · Posted: Mon Nov 02, 2009 1:44 pm Post Subject:

Thanks for the replies, appreciated.

Can anyone advise the best way to achieve building regs with vaulting the ceiling with a lean to roof in respect of insulation ??

freddymercurystwin · Posted: Mon Nov 02, 2009 2:06 pm Post Subject:

Rigid insulation such as Kinspan or Celotex would be best http://www.insulation.kingspan.com/uk/pdf/tp10.pdf see figure 1c. For an extension roof you need to achieve a U value of 0.20 so go down to the table that applies to fig 1c and you'll see that you need around 90-100mm between the rafters and 25mm below depending on the rafter spacings.

nathanw · Posted: Mon Nov 02, 2009 2:32 pm Post Subject:

thanks again for the reply.