Roofs Flashcards
What is a ‘cold roof’?
Thermal insulation is located between theceilingjoists meaning that everything above the insulation, such as the rafters, and anyroofspace, will be colder than the living space below it.
What is a ‘warm roof’?
The insulation layer is laid on top ofroofstructure.
Name 8 terms used to describe the various parts of a pitched roof?
- Valley
- Ridge
- Hip
- Hipped End
- Roof slope
- Verge
- Gable end
- Eaves
What do firming pieces create?
A sloping surface on a roof
What two things can firming consist of?
- Tapered lengths of fir (softwood) nailed to the top of each joist
- Varying depth lengths of softwood nailed across the joists
How do we ensure that frames resist racking or falling over?
By utilising cross bracing, gable end walls for bracing, whipped ends for bracing
Hip tiles are nailed to what?
The hip rafter
What is the typical width for lead Valley gutters?
125mm
Tiling battens are typically what size?
38 x 25mm
Slates are typically nailed to what size of batten?
50x25mm
Roofing felt is laid under what?
Timber battens
Ridge tiles are usually bedded in what?
Mortar
A low-pitched roof is typically between what two degrees to the horizontal?
10 and 30 degrees
The principal coverings for low pitched roofs are what?
Copper and aluminium strips 450 or 600mm wide (both of which are comparatively light in weight and therefore do not require heavy timbers to support them).
Can copper and aluminium sheets be bent without damage to the material?
Yes
In timber roof construction the insulation boards are nailed directly to the rafters. The counter battens over the roofing felt (DPM) and insulation is fixed how?
By nailing through the insulation to the rafters.
A roof is defined as flat when its weather plain is finished at a slope of what degrees?
Between 1 and 5
In a flat roof, timber joists are generally spaced at what centres?
400 to 600mm centres
What is rough boarding?
When boards are left rough surfaced from the saw
In sheet metalwork the word dressed describes what?
The shaping of the sheet
Where the lead flat roof is surrounded on all sides by parapet walls, where do we collect the rainwater?
At the lowest point on the roof
What is a wood roll in a lead flat roof?
A Wood Roll is used to provide a watertight expansion joint between two separate sheets of Lead.
The usual thickness of copper sheet for roofing is what?
0.6mm
The standard size of sheet for copper roofing are what two sizes (L x W)?
- 1200 x 900mm2. 1800 x 900mm
The minimum fall for a copper covered roof is what?
1 in 60 ( firming pieces used to create fall)
What is the cheapest metal used for roofs?
Zinc
Name two materials that have been used as a waterproof membrane for timber framed roofs?
- Asphalt - as a continuous membrane
2. Bitumen felt - laid in layers to form a membrane or skin.
Bitumen felt is generally used on what type of roofing?
Flat
