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Forces in a gambrel roof

:)

But not the felt - I hate felt...

Reply to
Tim Watts
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No - best case. You only measure from the *highest* ground point. Any part of the building that is lower is "for free".

Which is reasonable as digging into the ground does not make things worse for the neighbours.

Reply to
Tim Watts

Right, so your ground drops 2m over the allowed range of PD so you can build something 2.5 + 2m high as long as you build it at the deep end? ;-)

Ask someone who needed to get their house underpinned!

I can see how you could dig out the ground on the uphill side as long as the building was no higher than 2.5m above the ground at the highest point. You couldn't have say the back at 2.5m and build the front up on a raised platform.

If you dug out 2.5m at the top of the slope you could have something

5m tall or if we do it at the deep end (if I understand you correctly) it could be 7m tall. ;-)

Cheers, T i m

Reply to
T i m

Having thought about it a bit more. You could add a substantial ridge board and purlins each end of which is supported down through the end walls. In that way you can get the Gambrel shape without excessive forces trying to splay the walls as the roof weight is "hung" off the ridge and purlins If you can get the purlins just above head height, then it should allow comfortable movement inside.

Bob

Reply to
Bob Minchin

Apparently - the technical nots on PlanningPortal seem very clear about it and I found an analysis (called planning loopholes) that agreed.

In either case, you could sink it into even level ground a foot or two subject to drainage.

I'd be hardpressed to undermine my neighbours from the corner of the garden :)

Reply to
Tim Watts

I agree...

Reply to
Tim Watts

Insulated box section rolled steel roofing. 12.5 deg. pitch. Prolly need the same trusses to meet snow load anyway. Can come in a tasteful slate blue...:-)

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Reply to
Tim Lamb

I'm not an expert, but I am not sure this is true.

In a traditional pitched roof, the apex is assumed to be pin jointed. So that the rafters produce an outward thrust where they rest on the walls, because when a distributed vertical load is applied they want to "flatten".

But when you add a tie beam, you have a triangular structure which can support a distributed vertical load, and convert it into two vertical loads, one into each wall, without a spreading force. The tie beam does not have to be at the bottom of the rafters.

In a gambrel roof, the fillets resist the bending moment which tends to make the structure "flatten". How rigid it is depends on the size of the fillets, and how well they are fastened to the main beams. Doesn't it become equivalent to the "Tee" structure drawn below in T's. The walls are drawn with W's

T T T TTTTTTTTTTTTTTTT W W W W W W W W

In reality there will be a small spreading force in the gambrel case because of flex in the joints.

Structural analysts please shoot me down in flames.

Reply to
newshound

Hmmmm, workshop "super basement" here we come ;-)

Reply to
John Rumm

Wonder if I can buy a cliff! 'With PP for a 8'x16' shed 20 stories high'

NT

Reply to
tabbypurr

I (think) I've always been envious of those who have house-footprint-sized basements, possibly more than I've been happy to have a loft space that is useable (not a mesh of balsa wood trusses all stapled together).

All good and dandy if your house isn't built on a flood plane.

(I saw some fairly local 'new build' houses going up near a river and they were flooded just after they had installed the damp-proof-course (ironically)). ;-)

Are there any countries where basements are the norm? You seem to see them quite a lot on American based films?

Cheers, T i m

Reply to
T i m

basements cost more than ground floors, so are common in high land price areas.

NT

Reply to
tabbypurr

*giggle*
Reply to
The Natural Philosopher

_Every_ house I've lived in, in the US, had a basement. One of them flooded badly a few times. Of course, it's a big country, and there are some areas where basements are not at all common.

Reply to
S Viemeister

So, did you still use it and if so what? Was there something that was done to stop it flooding or was it just a matter of pumping it out (automatic pump possibly)?

Thanks for the feedback.

Cheers, T i m

Reply to
T i m

I had a colleague who lived in Canada for many years, he said that the norm for houses there was for everything to have a basement, except that it was usually at ground level. So all the normal living space was first floor or above. The "basement" was for the workshop, the laundry room (with a drain in the floor), the car as well as storing garden tools, bicycles, etc. Sounded very civilised.

Reply to
newshound

I've seen those that are sort of sunken into the ground with the basement having just a small window at ground level.

I've also seen those where the house is on a slope so one end is fully submerged (ala typical basement) whilst at the other it's 'at' ground level. ;-)

That's also something you are now seeing when houses are built next to rivers.

Doesn't it just ... and you can see why some pay *millions* to have one fitted underneath an existing house! ;-(

Now, that could be an interesting boundary dispute!

Cheers, T i m

Reply to
T i m

We put everything important up on platforms. Lots of pumping, and a dehumidifier. The washer, dryer, boiler, hot water cylinder and main freezer live down there. Our place in Scotland has no basement. I miss the extra space, but I don't miss dealing with wet messes.

Reply to
S Viemeister

So when you say 'flooded' you don't typically mean 'to the ceiling' then?

Understood.

I've often seen reference to people (Americans) having the 'furnace' in the basement so is / can that be the same as what we would typically call 'a boiler' or are they specifically only when the heating system uses blown air?

I was thinking on from that and I guess the value of a basement may depend on if the country you happen to live in has a high water table or not? Over here you hear of basements having to be 'tanked' and potentially drains would be more likely to let water in than out?

Cheers, T i m

Reply to
T i m

No, fortunately. When the alarm goes, we get the pumps going. Floods wouldn't be likely to reach the ceiling, though - the ceiling is a couple of feet above ground level.

'Furnace' is often used for what in UK would be called a boiler.

Areas with combined storm and sanitary drains/sewers can be a problem in flood conditions, but it's my understanding that new(er) construction requires backflow valves. There are always some people, though, who don't understand that if they flush the toilet when the land is flooded, filthy water may bubble out of the basement washtub... It's not the flood water coming _in_, it's the toilet water which can't get _out_.

Reply to
S Viemeister

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