How Can I Calculate How Many Roof Slates I Need?

Bluscreendream

Hi all,

I'm looking for some help calculating the amount of slates I need for a new kitchen roof. The roof area is exactly 30 feet X 20 feet. The slates I want to use are 1 foot X 2 foot. Could somebody in the know give me an approximate idea of how many of the these slates I would need? Many thanks.

obliviousgrudge

300 if my sums add up.

Bluscreendream

Thanks emmetmcl, I'm getting completely different quantities from different people on this Thanks for reply though.

obliviousgrudge

I did it like this:

30x20=600ft squared
1x2= 2 ft squared.

600/2=300 tiles.

Hope this helps.

Tefral

emmetmcl wrote: »

I did it like this:

30x20=600ft squared
1x2= 2 ft squared.

600/2=300 tiles.

Hope this helps.

This is correct. However you also need to take account of the Lap. 100mm or 4 inches is normal.
Also allow 10% for breakage.

Dupont

your slates might be 2ft long but if they are ordinary asbestoes slates they cover 10 inches including the over lap,so divide the height of roof by 10(20ft X 12=240inches divide by 10=24 rows of slates,30X12=360,360 divide by10=36 slates from left to right 36X24=864 i think thats it

Tefral

OP can you tell me if the roof is 30ft long and 20ft wide or visa versa? Ill do a little sketch and see..

Bluscreendream

Hi emmetmcl and cronin_j,

Thanks so much for the great info, I'm feeling much more confident now you wouldn't believe some of the quantities I had been given by certain folk.

cronin_j, considering the overlap of 4 inches, what in your opinion would this push the approx total quantity of slates up too? (I'll then add 10% for breakage)

many thanks

Tefral

Since im only a youngun I hate working in Ft so i worked it out thus.

30 Ft x 20ft is 600Ft.

600ft is 55.742m2

Round to 55.8m2 (always round up in these situations)

your Slates are 600mm x 300mm (24inches x 12inches)

Your going to need 12.3655 slates per m2 so that means

12.3655 x 55.8 = 689.99 (so 690 slates)

Then add 5% for wastage (i said 10% before but its quite a few slates and you wont break that many, the only ones that tend to break are a few along the bottom of the bales.

so:

690 slates + 35 slates = 725 slates

Bluscreendream

Hi Dupont,

Thanks for the post. The slates are not asbestos, the are totally black, quite shiney (on top) and would be about 3mm in thickness.


Hi cronin_j

Just to answer your previous question, the roof is 30 feet in lenght by 20 feet wide. Thanks a million for the in depth breakdown I really appreciate it, I'm actually helping my dad calculate this so that's were I'm getting the imperial measurements from lol Many thanks again for all your help.

Tefral

Bluscreendream wrote: »

Hi Dupont,

Thanks for the post. The slates are not asbestos, the are totally black, quite shiney (on top) and would be about 3mm in thickness.


Hi cronin_j

Just to answer your previous question, the roof is 30 feet in lenght by 20 feet wide. Thanks a million for the in depth breakdown I really appreciate it, I'm actually helping my dad calculate this so that's were I'm getting the imperial measurements from lol Many thanks again for all your help.

Ya i figured as much the rule is Length x breath x height, most people do this by nature but its always prudent to check.

No worries I get the same working with anyone older than 40 ha ha.. I work as a Quantity Surveyor and the boss was giving me diameters for pipes in inches and I jokingly said "Jesus will ya give me them in mm we are metric now" he turns around and says to me in front of the whole office, I bet if a girl asked you about inches youd be able to answer her ha ha

leet44

Bluscreendream wrote: »

Hi Dupont,

Thanks for the post. The slates are not asbestos, the are totally black, quite shiney (on top) and would be about 3mm in thickness.


Hi cronin_j

Just to answer your previous question, the roof is 30 feet in lenght by 20 feet wide. Thanks a million for the in depth breakdown I really appreciate it, I'm actually helping my dad calculate this so that's were I'm getting the imperial measurements from lol Many thanks again for all your help.

20 ft wide equals 20 slates, 12inch overlap means 30 rows, so 600 + 40 ish for breakages

Tefral

leet44 wrote: »

20 ft wide equals 20 slates, 12inch overlap means 30 rows, so 600 + 40 ish for breakages

Dont forget not only is there and overlap from top to bottom but once you go past the first row there is also an overlap from right to left to cover the tiles below.

Have a look here:

martin46585

As already posted, the slates cover 10" high though they cover 12"across, plus an extra row, and some times two, at the gutter, so it is 240"/10"plus two extra row is 26 times 30, plus the width of the gable soffit, plus over hang, which will take another three slates, makes it 26 * 33 = 858.....does this make sense................858

Bluscreendream

cronin_j wrote: »

No worries I get the same working with anyone older than 40 ha ha.. I work as a Quantity Surveyor and the boss was giving me diameters for pipes in inches and I jokingly said "Jesus will ya give me them in mm we are metric now" he turns around and says to me in front of the whole office, I bet if a girl asked you about inches youd be able to answer her ha ha

Ha ha, pure classic

Tefral

martin46585 wrote: »

As already posted, the slates cover 10" high though they cover 12"across, plus an extra row, and some times two, at the gutter, so it is 240"/10"plus two extra row is 26 times 30, plus the width of the gable soffit, plus over hang, which will take another three slates, makes it 26 * 33 = 858.....does this make sense................858

I have not taken into account for the gable soffit width and the overhang to the gutter as the OP just gave the dims and I just based it on that. However, OP if you havent included for this in your 30 x 20 measurement then you will also need to add in for this.

Bluscreendream

cronin_j wrote: »

I have not taken into account for the gable soffit width and the overhang to the gutter as the OP just gave the dims and I just based it on that. However, OP if you havent included for this in your 30 x 20 measurement then you will also need to add in for this.

The 30x20 dim factors in the gable soffits and overhang to gutter, Thanks again for the heads up though and all the calculations, it's greatly appreciated.

leet44

did I win?:rolleyes:

Dupont

cronin_j wrote: »

Dont forget not only is there and overlap from top to bottom but once you go past the first row there is also an overlap from right to left to cover the tiles below.

Have a look here:

i think the op is using slates so there is no over lap(yes they are lapped half) but say you start with a full one on the right the next row above you will use a half then full then half and so on so it still only takes that amount to go across the roof

martin46585

Bluscreendream wrote: »

The 30x20 dim factors in the gable soffits and overhang to gutter, Thanks again for the heads up though and all the calculations, it's greatly appreciated.

The first row will be two layers on top of each other, well a half slate then a whole slate on top, and is the same detail whether there is a soffit or not.........

gman2k

Bluscreendream wrote: »

Hi all,

I'm looking for some help calculating the amount of slates I need for a new kitchen roof. The roof area is exactly 30 feet X 20 feet. The slates I want to use are 1 foot X 2 foot. Could somebody in the know give me an approximate idea of how many of the these slates I would need? Many thanks.

You contact the technical department at Tegral (support@tegral.com) or 059 8631316, and you tell them the dimensions of the roof - measure in metric, and also, the roof pitch.
They will give you the quantity you need.
BTW, make sure your roofer uses non ferrous nails and accessories for the slates i.e. copper, stainless, or aluminium. Never galvanised.

Dupont

gman2k wrote: »

You contact the technical department at Tegral (support@tegral.com) or 059 8631316, and you tell them the dimensions of the roof - measure in metric, and also, the roof pitch.
They will give you the quantity you need.
BTW, make sure your roofer uses non ferrous nails and accessories for the slates i.e. copper, stainless, or aluminium. Never galvanised.

wery good point.if a slate where to get broke and you had to use a slate ripper to get under the slates and cut off the nails,if galvinised steel nails were used you will loosen the surronding slates trying to cut true the nails

Bluscreendream

Thanks guys for the extra info, gman2k, thanks a mil for the number and the tips on the nails.

Merch

I see there is a wire hook in the slate roof tiles, I see plenty of slate roofs that do not appear to have this at all? also is anything similar required for a tile roof? Im just wondering what stops them being lifted in a strong gust? is it their weight??

truebluechippy

13 slates per m2 that incl waste.