Walls Flashcards
The majority of walls are constructed using what 4 methods?
- Load bearing masonry
- Timber
- Steel
- Concrete
Name 5 typical thermal bridges you might see in a cavity wall / window detail
- No insulation at the masonry reveal
- Single glazing
- Metal window frames
- Where there is gaps in the insulation
- Where mortar has dropped onto the cavity tie
What are the two types of sound penetration?
A. Impact sound
B. Airborne sound
What dimensions are counter battens for timber slate walls?
50x25mm
Name two things that can cause render on external walls to crack
- Temperature changes
2. Moisture Movements
How do we minimise cracking in rendered external walls?
- By reinforcing the rendering with a mesh securely fixed to the wall
- By placing movements joints at no more than 6m centres
How are wall tiles spaced in a wall?
900mm horizontally and 450mm vertically
How are wall ties spaced around the sides of openings?
Around 300mm around the sides of openings
The cavity in loadbearing masonry construction is typically how thick?
50mm
Insulation retaining wall ties usually have what fixed over them?
Plastic wheel clips
Name the three types of surface finish for wood
- Paint
- Varnish
- Stains.
What is a cavity barrier?
A cavity barrier means any construction provided to seal a cavity against the penetration of fire and smoke or to restrict its movement within the cavity.
In order to inhibit fire spread in a cavity, every cavity within a building should have cavity barriers with at least a short fire resistance duration. Name 4 places where these should be installed.
- Around the edges of the cavity.
- Around the head, jambs and cill of an external door or window opening.
- Between a roof space and any other roof space
- Between a cavity and any other cavity (such as at the wall-head between a wall cavity and a roof space cavity).
What is the standard brick size in the UK?
215 x 102.5 x 65mm
What size is the standard brick mortar joint?
10mm
What size is the standard blockwork size in the UK?
440 x 215 x 100mm
What are non standard bricks called?
Specials
Why are special bricks less commonly used in construction?
Because they are more expensive and take longer to produce
Name 3 different brick types
- Clay fired bricks
- Calcium silicate bricks
- Concrete bricks / blocks
What is the recommended size of movement joint for a clay fired brick?
12mm
What is the recommended size of movement joint for a calcium silicate brick?
7.5 - 9mm
What is the recommended size of movement joint for a concrete brick / block?
6mm
In what two locations does cracking usually occur on the facade due to expansion and contraction in the building?
- On the short returns of walls
2. Underneath window sills
Where is it best to locate movement joints?
Where there is lateral support provided by internal walls
What two ways are wall tiles placed at locations where there is a movement joint?
- At 300mm centres where there is lateral support
2. Over the individual masonry leaf
There is no way of preventing the absorption of soluble salts from the ground by brickwork below the horizontal dpc level. However, how can we reduce this effect?
By using dense bricks below the dpc
The height of one concrete block coincides with the height of how many bricks?
3 Bricks
For non-loadbearing partitions, what are the dimensions of concrete blocks?
440x215x75mm
What is jointing?
The finish of the mortar joints between bricks.
Name the 4 most common mortar joints?
- Flush
- Bucket handle
- Struck
- Recessed
Lintels with a clear span of 1200mm or less must have a minimum bearing of what?
100mm
Lintels with a clear span above 1200mm must have a minimum bearing of what?
150mm
How do we close the cavity at a wall opening?
Using a cavity closer
What two things does a cavity closer do?
- Insulates the cavity
2. Acts as a vertical DPC
What is an alternative to solidly filling the cavity at jambs with cavity closer?
Using the Window or door frame to cover and seal the cavity
When using a metal window frame to seal the cavity, how do we seal the junction between the metal frame and the external masonry?
Apply a mastic seal at the point where they meet
Most loadbearing brick or block work walls over openings are supported by what?
Steel Lintels
It has become common practice to build in some form of damp-proof course or tray of flexible, impermeable material to direct any water out to the external face of walls. Where is this DPC typically located?
Over the head of windows
Every cavity should be divided by cavity barriers. What is the maximum distance between cavity barriers where the cavity has exposed surfaces?
Not more than 20m
Cavity barriers are not necessary to divide a cavity formed by two leaves of masonry or concrete at least how thick?
75mm
A timber stud wall is fixed vertically between what two things?
A timber stud wall is fixed vertically between what two things?
In a timber stud wall the vertical timbers are usual fixed at what two centres?
- 400mm or
2. 600mm
In a timber stud wall, what is used to stiffen the studs against movement that could cause finishes to crack?
Noggins
What is often applied to both sides of am insulated timber stud panel to provide lateral stability?
Plywood Sheathing
What is the purpose of breather paper?
To act as a barrier to water and at the same time allow the release of moisture vapour under pressure to move through the sheet.
Plywood sheathing is used to brace the stud wall in what direction?
Diagonally
The sole plate of the lower stud frame bears on what?
The foundation
The head of a timber frame supports what?
The floor joists
As a barrier to warm moist air what should be fixed on the warm side of the insulation?
A Vapour Control Layer
