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Author Topic: What defined the pitch of the average house roof?  (Read 7738 times)

Offline peppercorn

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Chicken or Egg type question.

Is the modern roof (in say Britain) a product of the need to hang tiles and stop water being blown under them...
Or a factor of what is needed to stop snow building up to dangerous weights in the winter?


Also, in terms of planning permission, is the height of the roof (and hence the building) a defining factor.  Hence if there is a general height of neighbouring buildings, etc setting a president to how high one can build, can a builder put in 3 stories with a flat roof instead?


 

Offline maffsolo

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What defined the pitch of the average house roof?
« Reply #1 on: 19/10/2010 14:09:37 »
Area rules and may determine building design and permits,
Ideally you want to keep the undesirable weather from entering the occupied area of a dwelling.
Future maintenance can be a factor also.

Footing stability for a structure is foremost important, the higher a structure the heavier it will be, and the ground needs to support it.

Civil Engineering information can tell you more exactly what is needed to know.
Zoning laws in the area will provide a baseline.
Variances, adjustment to the zoning laws, may need to be addressed, and how to go about it in that area.

 
 

Offline Geezer

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What defined the pitch of the average house roof?
« Reply #2 on: 19/10/2010 16:25:11 »
In some parts of the US, snow load has a lot to do with it. We had quite a lot of structural failures around here a couple of years ago, although I think they were nearly all large commercial buildings with flatish roofs. If you don't move the snow off them before it exceeds the design lmits, they can, and do, collapse.
 

Offline maffsolo

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What defined the pitch of the average house roof?
« Reply #3 on: 19/10/2010 18:51:07 »
Usually the News concentrates their effort that lean to sensationalism commercial buildings which affect more of the public will always focus and mostly get their attention. 

http://www.gsmroofing.com/images/uploads/snowLoading.pdf
.

Here is an extreme pitch that will combat  the fatal weight of snow.
.

.

.
Workers remove snow from the roof of Cactus Cantina,
a restaurant on Wisconsin Ave, NW (photo: Samara Martin Ewing, 9NEWS NOW).

Like Geezer says

 
In some parts of the US, snow load has a lot to do with it. We had quite a lot of structural failures around here a couple of years ago, although I think they were nearly all large commercial buildings with flatish roofs. If you don't move the snow off them before it exceeds the design lmits, they can, and do, collapse.
 

Offline peppercorn

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What defined the pitch of the average house roof?
« Reply #4 on: 19/10/2010 19:02:06 »
Yeah, the snow's not quite as prevalent in England (not saying anything about Scotland or Wales though!), but I guess we could have collapses.

I was wondering about weather flat roofs or shallow pitches could have automated heaters to stop too serious build up (can't see it being able to weigh the snow though ::)).

...

On a related note how expensive is toughened glass in largish sheets, compared with tiles or pitch (versus it's lifetime) - afterall it's only (mostly) sand and it can be fitted in metres at a time ;D
 

Offline Geezer

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What defined the pitch of the average house roof?
« Reply #5 on: 19/10/2010 19:23:22 »
I think some commercial buildings with flat roofs do have methods to melt the snow off. They might just be manually controlled, although it would not be hard to put a strain gage on some trusses to measure the load and activate the heaters.

Electric heating elements are common even on roofs which have a steep pitch. They are mounted just above the gutter. The idea is to prevent the dreaded "ice dam" which can easily bring down the ceilings in a home.

Anther common approach is to use a metal roof with a steep pitch. The snow tends to slide off, although that is not without some danger. A lady not far from here was buried and killed by such an avalanche two years ago when the snow slid off her roof.
 

Offline maffsolo

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What defined the pitch of the average house roof?
« Reply #6 on: 19/10/2010 22:13:15 »
Yep there is commercial and resident grade electric thermal tape, deicing roofs and gutters.
Google will have sources.
 Steel Roofing technology is much better than the earlier years, powder coating not galvanized, has a better life span.
How ornate do you want the roof? Toughen glass? Why not glass dormers?
« Last Edit: 19/10/2010 22:31:14 by maffsolo »
 

Offline peppercorn

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What defined the pitch of the average house roof?
« Reply #7 on: 20/10/2010 10:06:39 »
Why not glass dormers?

 :D :D

What;s the adage about folks with glass ceilings not throwing stones???


I just was thinking that float glass tech is fairly mature now and a day like today in London where it's a little cold but as blue as you like - I think the back of our North backing property could be so much inviting if the building had glass roof panels and light-tubes or some such - plus concentrated PV could be easier to setup....  just blue-sky thinking here  ;D
 

Offline maffsolo

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What defined the pitch of the average house roof?
« Reply #8 on: 20/10/2010 12:02:27 »
Yes glass houses and stones, ironic that both are made from sand... ::)
Peppercorn, what are you looking for or rather what do you desire in the style of the building?

Building/constructing a green house, fully equipped with plants, mammals, birds and bees.
« Last Edit: 20/10/2010 12:05:47 by maffsolo »
 

Offline peppercorn

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What defined the pitch of the average house roof?
« Reply #9 on: 20/10/2010 12:33:17 »
Building/constructing a green house, fully equipped with plants, mammals, birds and bees.

Yes, I'd like to also include some atmosphere, weather, some gravitation and day/night cycle :D

I just wonder in this day and age whether we are still better off covering our roofs with multiple ceramic squares, or can we be cleverer (for approx. the same cost)?
 

Offline Mazurka

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What defined the pitch of the average house roof?
« Reply #10 on: 21/10/2010 12:20:21 »
Different roofing materials and tile shape and size have different minimum pitches.  This has mainly been determined emprirically. (One of the slate quarries I visit has a series of buildings that it tests different pitches of roofs on). 
It also varies across the country - on a recent visit to London I was amazed at how many flat or shallow pitched roofs there were as compared to the rainy north!

Glass roof construction is perfectly feasable, but more expensive and as pointed out can be difficult design in a sensible way to avoid wide swings in temperature.    Historically, small pane size and insulation issues have been big factors agaisnt glass roofs as well as difficulties in waterproofing between panes/ frame...
 

Offline maffsolo

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What defined the pitch of the average house roof?
« Reply #11 on: 21/10/2010 17:35:00 »
Building/constructing a green house, fully equipped with plants, mammals, birds and bees.

Yes, I'd like to also include some atmosphere, weather, some gravitation and day/night cycle :D

I just wonder in this day and age whether we are still better off covering our roofs with multiple ceramic squares, or can we be cleverer (for approx. the same cost)?

Ah yes all 4 seasons climate controlled, anti gravity adjustability, supreme for the moving of heavy objects, indoor cross country skiing, little down hill with lifts, sun bathing at the island beaches of the simulated Mediterranean, Safari landscape doubles as a garden center during monsoon season. 24 hr day play and an 8 hr night sleep. Just have to watch for Lions, Tigers and Bears; tin man scare crow and Toe Toe. Who said Kansas?

All specialty and custom built to order items as advertised at the maximum cost overrun estimate:
Best price in town... [:o)]

All kidding aside contractors have a standard way any deviation from their standard convention to try to be clever  adds cost and puts a cleaver to your wallet permitting a financial spillage

« Last Edit: 21/10/2010 17:48:42 by maffsolo »
 

Offline peppercorn

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What defined the pitch of the average house roof?
« Reply #12 on: 22/10/2010 14:36:40 »
Glass roof construction is perfectly feasable, but more expensive and as pointed out can be difficult design in a sensible way to avoid wide swings in temperature.    Historically, small pane size and insulation issues have been big factors agaisnt glass roofs as well as difficulties in waterproofing between panes/ frame...

I'd like to see how a roof, at least partly glazed (large south-facing single-span glass panels) would work out when combined with light tubes and/or concentrated solar PV & hot-water - all intelligently controlled for optimum temperature, of course.
 

Offline maffsolo

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What defined the pitch of the average house roof?
« Reply #13 on: 23/10/2010 03:51:07 »
You must be looking for something like this

http://www.greenhomebuilding.com/growyourfood.htm
 

Offline Geezer

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What defined the pitch of the average house roof?
« Reply #14 on: 23/10/2010 06:08:14 »
or, something like this

 

Offline peppercorn

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What defined the pitch of the average house roof?
« Reply #15 on: 23/10/2010 10:41:52 »
You must be looking for something like this

http://www.greenhomebuilding.com/growyourfood.htm

Or this:
http://en.wikipedia.org/wiki/Trombe_wall


Geezer - Re: your suggestion, at least the rent will be lower than my current flat :D
 

Offline Geezer

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What defined the pitch of the average house roof?
« Reply #16 on: 23/10/2010 10:50:26 »
Looks like a bijou residence to me.
 

Offline peppercorn

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What defined the pitch of the average house roof?
« Reply #17 on: 23/10/2010 11:02:44 »
Looks like a bijou residence to me.
I always said I wanted to live in a 'green' house!
 

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What defined the pitch of the average house roof?
« Reply #17 on: 23/10/2010 11:02:44 »

 

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