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A roof height and angle

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devonwoody

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I have a double garage with corrugated asbestos leanto roof. I would like to change the roof to tiled (concrete tiles). The width of the garage is
5.50mtrs. Can anyone tell me what height is needed at the present roof level to put up a pitch roof with these tiles.
I am also wanting to keep the maximum height below the 4 mtrs. height because I assume that planning permission would not be required for under this height.
 

ike

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DW,

Two bits of info are needed'

1.What make of tile will you use?. You need to know the minimum roof pitch.
2. what is the height to the eaves?

Ike
 

devonwoody

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Thanks for the warning, but I have already been exposed to the risk ( resided here for 20 years) so I might as well dismantle myself with some precautions.
Also I believe that the council must accept asbestos material from a resident, its different if a contractor does the work?

Any adverse comments accepted.
 

devonwoody

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I want a tile which allows me to have the lowest pitch possible. The present wallplate level is 90" tilting down to 81".
 

cambournepete

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devonwoody":1v6ty6xz said:
Thanks for the warning, but I have already been exposed to the risk ( resided here for 20 years) so I might as well dismantle myself with some precautions.
Also I believe that the council must accept asbestos material from a resident, its different if a contractor does the work?

Any adverse comments accepted.
I think the risk is minimal if you don't touch them, as you're not disturbing the fibres, but as soon as you try and move the asbestos then you will be disturbing the fibres, with potentially serious health hazards. This is what I understand, butb it might be complete cobblers of course.

I'd check with your local council.

Pete
 

ike

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DW,

Depending on tile pattern, interlocking concretes tile require minimum 15 deg pitch (e.g Marley Wessex), typically around 22.5 deg for many patterns esp. pantiles.

For 5.5m spam:-

@ 15 deg pitch - rise to apex = 710mm
@ 17.5 deg pitch - rise to apex = 830mm
@ 22.5 deg pitch - rise to apex = 1050mm

So with your ceiling height = existing upper wallplate (2300mm approx), you will be comfortably under 4m. If you construct your own trusses the following info might be some help http://www.dontim-eng.co.uk/technical_mitek.php4. I'd recommend you design just below the maximum 4m. The roof will be stronger and you can reduce the rafter/joist/brace dimensions. To the above dimensions - these are just simple triangulations. Add on for the cross sectional depth of the rafter/batten tile above the wallplate.


Ike
 

ike

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Oh, and I used the 5.5m span not including any overhang. I'll recalculate for you if you can give me more information.

NOTE: I am not offering any structural calculation. I have however designed and built truss framed roofs for both my house and workshop, and they haven't shown any signs of distress yet!

ike
 

Mike.C

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Hi Devonwoody,

Cambournepete warning is correct. Your asbestos roof is ok sitting there for 50 years and it will not harm you but the minute you say drill into it your health is at risk.

The trouble is the longer it has been up the more brittle it becomes and when you try to remove it there is a good chance it will break and bits of asbestos will fly about, and the way they look at it it is not only your health at risk but also those close by.

As for removing it i am not sure if you need a specialist company. I seem to remember that you can hire a specialist skip and after you have finished the company take it away and deal with it as a toxic substance.

If you can remove it yourself then use a hose pipe to keep it wet. This way there is less of a chance of the fibre's flying around and make sure you ware a mask.

Good Luck with the new roof.

Regards

Mike.C
 

simuk

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Hello Devonwoody,

If you are going to dismantle it yourself, then probably a good idea to spray the sheets first with pva mixed with water. Keep breakage of the sheets down to a minium.


Simuk
 
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Anonymous

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After i attended an asbestos awareness course for my job i can still only when fully protected (full suit,hood,mask,gloves,overboots,hepafiltered vacuum(asbestos rated) and my trusty spray bottle with a pva mix). any asbestos products i remove has to be double bagged in rubble type sacks sealed with hazard tape and labeled and left on site ,because i am not registered to carry hazardous materials that has to be done by a specialist company .only work 1 hour per week in that enviroment .If you knowingly disturb/destroy asbestos you are not only putting yourself at risk but any one near you .Exposure is not an option you may also be liable for a trip to court ,asbestos related diseases can occur upto 25 year after exposure. I know 1 person i have worked with in the past has died from an exposure to asbestos from removing an old shed for his dad 15 years ago .I suppose he thought like the rest of us well been around it for years an it ain't killed me yet .Life is a one time show my friend .To die once is once too often .Either leave it alone unless you plan to seal it (spray not brush with correct safety equipment) or get it removed properly .Ask the council in exeter they have a team of guys that do it .
 

Dewy

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Is this a flat roof with a slight slope front to back for the water runoff?
Plus, what is the garage made of? Is it brick/block or sectional concrete?
If it's this type of structure then the rear will be lower than the front making it difficult to alter the roof type as you will need the garage walls to be horizontal.
Also. Are you certain the roof is asbestos? My next door neighgbour has the same make sectional garage as me but his was erected over 35 years ago when asbestos was used a lot. Mine was erected 10 years ago & has a corrugated concrete roof that looks like asbestos but isn't.
 

Karl59

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There are three types of asbestos that you should be aware of, Brown, Blue and White each being easily identified by its colour.

Of the three the blue and brown are classed as the most dangerous and were banned some 20 years ago. White asbestos (chrysotile) whilst still dangerous is the least dangerous of the three and its use was only banned, except for some specialist uses, in 1999.

You will find that the asbestos sheets used for roofing are normally classed as low risk as the fibres are bonded within the cement and as such you do not need to be licensed to work on it. However you MUST, I repeat MUST take precautions if you intend to remove it yourself.

DO NOT USE POWER TOOLS.

DO NOT BREAK UP LARGE SHEETS.

DO NOT TAKE CONTAMINATED PROTECTIVE CLOTHING INTO YOUR HOME.

DO NOT EXPOSE LOVED ONES, FRIENDS OR NEIGHBOURS TO UN-NECESSARY RISKS BY IGNORING THE ABOVE POINTS.

DO WEAR DISPOSABLE PROTECTIVE CLOTHING.

DO WEAR A SUITABLE FACE MASK (APPARENTLY A DUST MASK IS OK, I WOULD GO FOR A FULL OR AT LEAST A HALF MASK WITH SUITABLE FILTERS MYSELF)

DO WEAR GLOVES

DO ENSURE THE SHEETS ARE KEPT DAMP, USE A WATER SPRAY TO ACHIEVE THIS.

Having gone through all that you will still need to dispose of the sheets correctly and therefore you must contact your local council offices and follow their advice and regulations.

This basic information was given to me by one of the HSE officers manning their stand at Inter Build in April. Whilst I relate it in good faith I would reccomend that you contact them directly to clarify any specific points you may have.

The HSE can be contacted by any of the following methods:

Infoline:-

Tel: 08701 545500
Fax: 02920 859260

Email: hseinformationservices@natbrit.com

Free HSE leaflets can be downloaded from their website www.hse.gov.uk.

I hope the above is of some help.
 

devonwoody

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The asbestos roof has a printed name"everite standard A C sheet"
and I would describe the colour as gray to white.



With regard to eaves, at present the roof is leanto shape and there are no eaves, and naturally any design needs minimum eaves to avoid undue height.

Thanks to all for their concern and very helpful advice.
 
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