Flat Roofs Flashcards
How are jiffy hangers secured to the joist?
30 – 40 mm twist nails
What defines a flat roof?
Pitch 10 degrees and below
Three ways the fall be achieved on a flat roof?
Tapered firings, diminishing firings, pitched joists.
What is the difference between a cold and warm deck roof?
Cold deck insulation between joists below decking. Warm deck insulation on top of decking.
How is the rain prevented from running off the edges of the roof and guiding it towards the gutter.
By using tilt fillets on the edges of the roof.
How can the decking board be secured to the joists?
Ring-shank nails or countersunk screws.
What is the purpose of the firing strips?
To provide a fall to the roof and drain the rain off.
What is the purpose of the restraint straps on a flat roof?
To tie the timber roof structure to the brickwork, wind protection.
How are the restraint straps secured in place?
30mm twist nails to timber and screws and plugs to brickwork.
At what span is a row of strutting required between joists?
Greater than 2.4m requires a 1 row of strutting and greater than 4.8 requires 2 rows.
What is the purpose of a drip batten on a flat roof?
Extends the roof over the gutter.
If the joist is bowed, how would it be positioned in the flat roof construction?
Positioned with the bow at the top of the joist.
Why must strutting between joists be kept 10mm from the top and bottom of the joist?
To prevent the strutting fouling the floor and ceiling coverings.
What is the purpose of ventilation in a flat roof?
To keep the moisture content below 18 percent and prevent rot and corrosion of metal fixings.
What is the purpose of strutting between joists?
Prevents joists twisting.
What material should be used to pack joists to get them level?
Slate or nylon packers
What governs the joist spacing?
The span and the thickness of roof covering.
State two methods of supporting joists?
Built-in, hangers, bolted wall-plate & steel joists.
What is the purpose of perimeter noggins in a flat roof?
To support the edge of the decking and ceiling coverings.
How is the rainwater prevented from puddling on a roof?
Firings are used to give the roof a fall.
What is the disadvantage of angling the joists to create the fall on a flat roof?
The ceiling slopes.
What part of the building regulations covers construction of flat roof construction?
Part A
What visual safety checks would you carryout on your circular saw before using it to cut the joists to length?
Check the body of tool for damage, check battery connections, check guard operates correctly, check cable for damage.
What health and safety regulations are complying with when installing joists.
HASWA, PUWER, WAHR, PPE reg, Manual handling regs, COSHH
