HsLBroker:
....

HsLBroker:
A home is gotten when you look for comfort based on your fantasy, but a shelter is a necessity, and a building becomes a shelter when it can prevent rain,water,sun, strong wind and other climatic elements from affecting the occupants- human,animal, living and dead loads with personal effects.

As far as I am concerned the moment you have your roof placed on a building, other things are important but they are basically needs. You can’t move into a house without a roof , but we have seen people living in a house with no window or makeshifts windows covered with ordinary bags and cardboards.

So it is very important to calculate the dimension of the true length of a roof members. These dimensions are essential to determine the accurate span of Rafter, Wall plate, Tie beam, King Post, Overhang, Purlins, fan struts etc.

Residential timber-framing construction clearly differentiate between spacing and span Spacing the centre-to-centre distance between structural members, unless otherwise indicated.

Span the face-to-face distance between points capable of giving full support to structural members or assemblies. In particular, rafter spans are measured as the distance between points of support along the length of the rafter and not as the horizontal projection of this distance.

Single span the span of a member supported at or near both ends with no intermediate supports.

Continuous span the term applied to members supported at or near both ends and at one or more intermediate points such that no span is greater than twice another.

Span/length calculation for roof members.

As can be seen the span of the rafter in the figure below is not quite in agreement with the Code but we will use the figures for the rafter span as calculated below.

Wood/ timber are sawn into various sizes amongst are

2” by 2” i.e 50mm by 50mm

2” by 3” i.e 50mm by 75mm

2” by 4” i.e 50mm by 100mm

2” by 6” i.e 50mm by 150mm

3” by 4” i.e 75mm by 100mm

3” by 6” i.e 75mm by 150mm

HsLBroker:
With the diagram above applying Pythagoras theorem

X2 (rafter length )=4.52+3.52

X=5.7m

Rafters are nailed side by side tie beam and struts. So we use the numbers of pieces of tie beams because they are also spaced at 1.2m center to center and multiply by 5.7m

15 pcs of rafter (same as tie beam) multiply by 5.7 =85.5m

Now divide by 3.6m to know the numbers of 3” by 4” to purchase in market=24 pcs of 3” by 4” required for rafters.

PURLINS are the wood of 2” by 2” or 50mm by 50mm we nail the roofing sheets on.

Purlins are spaced based on designs or type of roofing sheets. But for our calculations, we are using 900mm spacings.

Going by diagram above add 5.7m +5.7m for both sides=11.4m

Divide 11.4m by 0.9m to know the numbers required =13 pcs of purlins of length 18.175m (The purlins has to span the length of the building which is 16.975 plus 1.2m for the overhangs by sides)

So 13 by 18.175m=236m

Now divide by 3.6m to know the numbers requires to purchase in market =236/3.6

=66 pieces of 2” by 2” to purchase in market for the purlins.

KINGPOST is that piece of wood that stands at the middle of two rafters falling at the opposing sides. Is the one that spans vertically from the tie beam/rafter line, so just the same way we calculated for rafter, remember 15 pieces and multiply by the height of the roof 3.5m=52.5m

Then divide by 3.6m to know the numbers to buy in the market.

Therefore 15 pieces of wood of 2″ by 6″ termed kingpost is needed to be bought in the market.

HsLBroker:
From the picture above you can see the height of the roof of building and the length and breadth of building is already shown in the floor plan, so left to be known is the rafter or the fall ‘x’ as shown in diagram above.

Remember the Pythagoras theorem in secondary school days used in calculating the longest part of a right angle triangle.

The numbers of wood to be calculated also depends on spacing for the purpose of this exercise, we are using the format in diagram above as our specifications for our calculations.

For ceiling noggins of 600mm centers it simply means the wood are nailed 600mm apart, so add the breadth of plan and 600mm as overhangs both sides i.e 7,800mm or 7.8m +1200mm or 1-2m=9meters

Then divide by 0.6m=15pcs of 16.975m of 50 by 50.

For the longitudinal portion, 16.975+1.2m(the overhangs of 0.6m both sides)=18.175m then divide by 0.6=31 pcs of 9m of 2” by 2” ( Note how the length on one side is used to calculate the pieces/numbers of wood required for the length of the other side)

So to know the number of 2 by 2 to buy in the market for the ceiling noggins-

18.175m x 15pcs=273m of 2” by 2”

9m x 31pcs=279m of 2” by 2”

Total=552m

In the market, the wood comes in 3.6m per piece

So 552/3.6=153 pcs of 2” by 2” timber to buy in the market for ceiling noggins.

WALL PLATE is the timber/wood that are placed on top of blocks or roof beams as the case may apply, so for the fastest way to calculate this, is to add the entire walls length and divide by 3.6m to know the numbers of pieces you need. I am using approximately 100m.

So for 100m, divide by 3.6=28pcs of 3” by 4” or 75mm by 100mm to purchase in the market for timber named wall plate.

For FACIAL BOARD, remember the length and breadth of the plan of the building with its overhangs of 0.6m each, so add the perimeter

9m+9m+18.175m+18.175m=54m

Divide 54m by 3.6m=15pcs of 1” by 12”

For TIE BEAM, going by the section, it was recommended that we lay the timber named tie beam which is 2” by 6” or 100mm by 150mm at 1.2m centers apart. So what we need to do is to follow the same format used in calculating the ceiling noggins but it is going to span only the breadth of 7.8m only.

So divide 18.175m by 1.2m centers (spacing)

=15pcs of 7.8m =117m, then divide by 3.6m to know the numbers to buy/purchase in market.

117/3.6=32pcs of 2 by 6 of wood termed as tie beam to buy in the market.

STRUTS are a bit complex to calculate, they are the members placed diagonally as shown in diagram to connect the rafter with tie beams. We can use the numbers of tie beams and multiply by 2-

i.e 32 pcs multiply by 2=64 pcs of 3 by 4 or 75mm by 100mm termed as struts to be bought in the market.

For RAFTER, check the height of roof and the breadth of plan to determine the rafter which is the falling portion of the roof (except is already given from the section)

Lets take the height of the roof as 3.5m and the breadth of plan plus overhang is 9m.

HsLBroker:
Still available

nnamxxx:
I need an estimate for quantity of wood to be used for roofing a five bedroom bungalow measuring 90ft by 23ft. I want the kingpost to be between 7ft to 8ft.

bissiejoe:
Please what is the current price for the following wood sizes

2 by 4
2 by 3
3 by 4

thanks

nnamxxx:
I need an estimate for quantity of wood to be used for roofing a five bedroom bungalow measuring 90ft by 23ft. I want the kingpost to be between 7ft to 8ft.

HsLBroker:



what type roofing sheet are you using determine the numbers of woods

do you have parapet or not sir ?

HsLBroker:
no respond

ak22:



Please what is the normal space measurement for Gerald logging ?

HsLBroker:
14 inches and quarter

ak22:


Thanks alot sir but if it is more than that nko like 15?

HsLBroker:
A home is gotten when you look for comfort based on your fantasy, but a shelter is a necessity, and a building becomes a shelter when it can prevent rain,water,sun, strong wind and other climatic elements from affecting the occupants- human,animal, living and dead loads with personal effects.

As far as I am concerned the moment you have your roof placed on a building, other things are important but they are basically needs. You can’t move into a house without a roof , but we have seen people living in a house with no window or makeshifts windows covered with ordinary bags and cardboards.

So it is very important to calculate the dimension of the true length of a roof members. These dimensions are essential to determine the accurate span of Rafter, Wall plate, Tie beam, King Post, Overhang, Purlins, fan struts etc.

Residential timber-framing construction clearly differentiate between spacing and span Spacing the centre-to-centre distance between structural members, unless otherwise indicated.

Span the face-to-face distance between points capable of giving full support to structural members or assemblies. In particular, rafter spans are measured as the distance between points of support along the length of the rafter and not as the horizontal projection of this distance.

Single span the span of a member supported at or near both ends with no intermediate supports.

Continuous span the term applied to members supported at or near both ends and at one or more intermediate points such that no span is greater than twice another.

Span/length calculation for roof members.

As can be seen the span of the rafter in the figure below is not quite in agreement with the Code but we will use the figures for the rafter span as calculated below.

Wood/ timber are sawn into various sizes amongst are

2” by 2” i.e 50mm by 50mm

2” by 3” i.e 50mm by 75mm

2” by 4” i.e 50mm by 100mm

2” by 6” i.e 50mm by 150mm

3” by 4” i.e 75mm by 100mm

3” by 6” i.e 75mm by 150mm

HsLBroker:
From the picture above you can see the height of the roof of building and the length and breadth of building is already shown in the floor plan, so left to be known is the rafter or the fall ‘x’ as shown in diagram above.

Remember the Pythagoras theorem in secondary school days used in calculating the longest part of a right angle triangle.

The numbers of wood to be calculated also depends on spacing for the purpose of this exercise, we are using the format in diagram above as our specifications for our calculations.

For ceiling noggins of 600mm centers it simply means the wood are nailed 600mm apart, so add the breadth of plan and 600mm as overhangs both sides i.e 7,800mm or 7.8m +1200mm or 1-2m=9meters

Then divide by 0.6m=15pcs of 16.975m of 50 by 50.

For the longitudinal portion, 16.975+1.2m(the overhangs of 0.6m both sides)=18.175m then divide by 0.6=31 pcs of 9m of 2” by 2” ( Note how the length on one side is used to calculate the pieces/numbers of wood required for the length of the other side)

So to know the number of 2 by 2 to buy in the market for the ceiling noggins-

18.175m x 15pcs=273m of 2” by 2”

9m x 31pcs=279m of 2” by 2”

Total=552m

In the market, the wood comes in 3.6m per piece

So 552/3.6=153 pcs of 2” by 2” timber to buy in the market for ceiling noggins.

WALL PLATE is the timber/wood that are placed on top of blocks or roof beams as the case may apply, so for the fastest way to calculate this, is to add the entire walls length and divide by 3.6m to know the numbers of pieces you need. I am using approximately 100m.

So for 100m, divide by 3.6=28pcs of 3” by 4” or 75mm by 100mm to purchase in the market for timber named wall plate.

For FACIAL BOARD, remember the length and breadth of the plan of the building with its overhangs of 0.6m each, so add the perimeter

9m+9m+18.175m+18.175m=54m

Divide 54m by 3.6m=15pcs of 1” by 12”

For TIE BEAM, going by the section, it was recommended that we lay the timber named tie beam which is 2” by 6” or 100mm by 150mm at 1.2m centers apart. So what we need to do is to follow the same format used in calculating the ceiling noggins but it is going to span only the breadth of 7.8m only.

So divide 18.175m by 1.2m centers (spacing)

=15pcs of 7.8m =117m, then divide by 3.6m to know the numbers to buy/purchase in market.

117/3.6=32pcs of 2 by 6 of wood termed as tie beam to buy in the market.

STRUTS are a bit complex to calculate, they are the members placed diagonally as shown in diagram to connect the rafter with tie beams. We can use the numbers of tie beams and multiply by 2-

i.e 32 pcs multiply by 2=64 pcs of 3 by 4 or 75mm by 100mm termed as struts to be bought in the market.

For RAFTER, check the height of roof and the breadth of plan to determine the rafter which is the falling portion of the roof (except is already given from the section)

Lets take the height of the roof as 3.5m and the breadth of plan plus overhang is 9m.

HsLBroker:
With the diagram above applying Pythagoras theorem

X2 (rafter length )=4.52+3.52

X=5.7m

Rafters are nailed side by side tie beam and struts. So we use the numbers of pieces of tie beams because they are also spaced at 1.2m center to center and multiply by 5.7m

15 pcs of rafter (same as tie beam) multiply by 5.7 =85.5m

Now divide by 3.6m to know the numbers of 3” by 4” to purchase in market=24 pcs of 3” by 4” required for rafters.

PURLINS are the wood of 2” by 2” or 50mm by 50mm we nail the roofing sheets on.

Purlins are spaced based on designs or type of roofing sheets. But for our calculations, we are using 900mm spacings.

Going by diagram above add 5.7m +5.7m for both sides=11.4m

Divide 11.4m by 0.9m to know the numbers required =13 pcs of purlins of length 18.175m (The purlins has to span the length of the building which is 16.975 plus 1.2m for the overhangs by sides)

So 13 by 18.175m=236m

Now divide by 3.6m to know the numbers requires to purchase in market =236/3.6

=66 pieces of 2” by 2” to purchase in market for the purlins.

KINGPOST is that piece of wood that stands at the middle of two rafters falling at the opposing sides. Is the one that spans vertically from the tie beam/rafter line, so just the same way we calculated for rafter, remember 15 pieces and multiply by the height of the roof 3.5m=52.5m

Then divide by 3.6m to know the numbers to buy in the market.

Therefore 15 pieces of wood of 2″ by 6″ termed kingpost is needed to be bought in the market.

HsLBroker:
it won't work, the roof will leak

ak22:


OK

abraolas1:
Hi HSLbroker

I will Like to ask if you have idea of how much a Cameroon Zinc roofing Sheet bundle cost now

I will Appreciate a Reply

Thanks