Maximum roof overhang

NickTellis

What is the maximum recommended roof overhang? We're thinking of completely replacing the old roof on our bungalow and ideally I like to extend it out as much as possible over the eaves which, along with a change in roof pitch, should help increase the useable living space upstairs.

topcatcbr

If you change the look of the roof you will require planning permission.

NickTellis

Yes I am well aware of that, thanks

topcatcbr

structurally there is no max

sydthebeat

NickTellis wrote: »

What is the maximum recommended roof overhang? We're thinking of completely replacing the old roof on our bungalow and ideally I like to extend it out as much as possible over the eaves which, along with a change in roof pitch, should help increase the useable living space upstairs.

as topcatcher states structurally anything can be built.... (ok i can hear sniggers).....

but regarding overhangs, theres no point having an overhang that extends further than the point at which it meets a 60 deg line from the floor...

this is usually the max overshading you can give a room to prvent overheating insummer....


see attached

muffler

NickTellis wrote: »

What is the maximum recommended roof overhang? We're thinking of completely replacing the old roof on our bungalow and ideally I like to extend it out as much as possible over the eaves which, along with a change in roof pitch, should help increase the useable living space upstairs.

Maybe Im missing something here but how is increasing the overhang going to add to attic space?

NickTellis

A good question and one I was going to post a seperate thread about but as we're all here... my thought was that as we're basically replacing the entire roof we might be able to extend the new joists out over the external walls by about 50 cms either side thereby adding a metre or so in width to the upstairs floor area. Any thoughts on this or is it a definite no no?

Slig

interresting idea. Its gonna make your roof look huge compared to the house
how do you propose to tie down the rafters to the wall?

NickTellis

How do I attach the rafters down? Well I was hoping you'd be able to tell me that
I've seen similar bungalows with the underside of the roof overhangs clad in wood so I'd like to do something similar to ours along with timber cladding on the new extension to give the house an "Austrian" vibe. Apart from gaining extra space in the attic the overhang would also provide a bit of extra shelter from rain and to a lesser extent the sun.

topcatcbr

NickTellis wrote: »

A good question and one I was going to post a seperate thread about but as we're all here... my thought was that as we're basically replacing the entire roof we might be able to extend the new joists out over the external walls by about 50 cms either side thereby adding a metre or so in width to the upstairs floor area. Any thoughts on this or is it a definite no no?

It is definatly possible but its not ideal. i can think of much better ways of achieving your goal.

topcatcbr

NickTellis wrote: »

How do I attach the rafters down? Well I was hoping you'd be able to tell me that
I've seen similar bungalows with the underside of the roof overhangs clad in wood so I'd like to do something similar to ours along with timber cladding on the new extension to give the house an "Austrian" vibe. Apart from gaining extra space in the attic the overhang would also provide a bit of extra shelter from rain and to a lesser extent the sun.

I think you should talk to an architect or tech
You are going to require planning permission anyway.

This can be done better at design stage.

NickTellis

topcatcbr wrote: »

It is definatly possible but its not ideal. i can think of much better ways of achieving your goal.

Well don't be shy

topcatcbr

NickTellis wrote: »

Well don't be shy

You need to sit down and have a conversation with someone who has the technical ability to design to your brief. I dont believe that this is the place for this type of advise (specific technical advise).

Just my opinion.

NickTellis

Thanks topcatcbr, I know what you're saying it's just that I'm doing up my own design on computer in as much detail as possible before handing it off to the architect/technician to do up the proper drawings for planning. If you say it's feasible then it's going into my design - that's the joy of the design stage, it doesn't cost you anything.

ircoha

The increase in the ridge height is the key element here as if you just widen the base of the triangle without raising the apex.... as u have CAD you know the rest.

There are a couple of additional opportunities here which should not be overlooked, including:
A wider overhang could be used to disguise some serious external insulation.
New roof => new enhanced insulation and airtightness, provision for solar thermal panels etc

if the span gets too big for normal timber have a peep at this stuff
http://www.jmcmahon.com/SilentFloorSystems.htm

it is also available for roofing, http://www.ilevel.com/floors/default.aspx
HTH

Mellor

Yop, spot on throughout


OP its possible, just awkward.

Mellor

ircoha wrote: »

The increase in the ridge height is the key element here as if you just widen the base of the triangle without raising the apex.... as u have CAD you know the rest.

There are a couple of additional opportunities here which should not be overlooked, including:
A wider overhang could be used to disguise some serious external insulation.
New roof => new enhanced insulation and airtightness, provision for solar thermal panels etc

if the span gets too big for normal timber have a peep at this stuff
http://www.jmcmahon.com/SilentFloorSystems.htm

it is also available for roofing, http://www.ilevel.com/floors/default.aspx
HTH

The first thing I thought of was making it non triangular, say mansard or double ridge.
Other wise I fear it would look strange

NickTellis

Thanks for the replies folks. Actually I don't have CAD, I doing up the design in a DTP package called FrameMaker but I can assure you it is all to scale. However, please understand that it's been 20 years since I did mechanical drawing in school.

With regard to increasing the side blockwork I'd already thought of that months ago but it's not really something I want to do as it'd mean completely exposing the ground floor during construction and to be honest it looks a bit "off". I'm looking into the idea of building the new roof over the old one, getting it to the felt/membrane stage and then removing the old roof as I've seen this done in another bungalow down the road. My other thought was to use something like the Smartroof system so everything is contructed off-site and installed in a day but that would mean removing the old roof first... and we all know factories experience delays in delivery.

Here's where my design currently is at. The parts in red are the proposed new additions, in the side elevations the smaller internal triangle is where the roof currently is so by adding 1.2 metres to the ridge height and extending the joists out by about 50 cms either side I'd gain some decent extra floor space and head height. Obviously the more I could extend out over the eaves the more usable floor space I'd get. Opinions appreciated as always.