What is the typical size of a UK brick?
65 x 102.5 x 215mm
Extra 10mm for mortar all around
What are three main materials in a brick?
Silica (sand) 50-60%
Alumina (clay) 20-30%
What are three typical brick bonds?
English ( row of stretchers, row of headers alternating)
Flemish (alternating headers and stretchers)
What are three common types of foundation?
What are three types of damp?
Three typical defects for a cavity wall…
Damp (rising, penetrating or condensation)
Wall tie failure
Cracking in bricks or mortar from movement or moisture
What issues can repointing old brickwork in cement mortar cause?
Older brick walls are designed to breathe and old lime mortar allowed this as it is porous, with new cement it will not allow moisture through so will cause the bricks to be saturated and cause problems such as frost attack. Also cement is less flexible and may not allow movement in the wall and cause cracking.
What is cold bridging?
Where there is a path for heat to transfer through an area of higher thermal conductivity. Common around floor to wall joints where there is insufficient insulation or breach cavities.
What is a cravity tray?
Cavity trays are a DPC that is used to direct moisture within the cavity out of weep vents, they are installed above openings so water can escape the cavity and not sit on the internal leaf.
How are floors typically fixed to walls?
Ground - often built into the inner leaf
Intermediate - joist hangers secured to the inner leaf
What issues can you get with timber suspended floors?
Poor sub floor ventilation can cause problems with eithe infestations of wood worm, or rotting on the timber due to excessive mositure. Air bricks could get blocked with new ground levels or material or not even have enough air bricks in place.
What is the difference between an older and a modern cavity wall?
Older cavities from the 1920-60s have teo skins of brickwork, thin cavities (50mm and under) and are often not insulated. Iron or steel wall ties that are likely to corrode.
Modern cavities from 1960 onwards have an outer leaf of brickwork and an inner of block work, the csvities are thicker and have insulation. Galvanised steel wall ties that are better protected of corrosion.
How can you tell the difference from a cavity or solid brick wall?
Often the brick bonds, a stretcher bond is likely a cavity and flemish or english can be solid.
Also the thickness of the wall, a cavity is going to be atleast 250mm plus, and a solid wall could be near 215mm, a 1 and a half brick solid walk could be 330mm so bond type should decide the walk construction.
The age of the building could also give indication. 1920’s onward cavity walls were more common.
What is subsidence?
It is the movement of ground and a building. It could be natural or human activities. Where a building or part would sink into the ground.
What is settlement?
It is the compaction or displacment of the soil below a building or load. Usually within the first few years of construction which is normal however it can vary.
What is the construction of a solid floor?
Starting from the bottom,
Insulation can be above or below of the concrete slab, it is not tied to the walls to allow for some movement.
Describe the construction of a concrete suspended floor?
Precase concrete T beams are suspended on hangers or built into the load bearing walls and soaced every 440mm for a block to be placed between. The gaps should then be grouted to inprove fire and sound resistance if used between flats.
It should have sufficient levels of ventilation to prevent moisture causing damp & insulation to improve energy efficiency.
How often should cavity wall ties be installed?
Every 450mm vertically & 900mm horizontally.
Around openings a 225mm maximum spacing.
What is a DPC and what does it do?
It is a damp proof course that is an impermeable memebrane to stop moisture transferring from the ground into walls, they should be installed at 150mm above ground level. They stop capillary action through masonry.
What is capillary action?
It is water that travels through small pores against gravity, in masonry it can rise to around 1.5m, this is what causes rising damp.
What is a lintel?
A horizontal structural beam that is installed to span over an opening to soread the above load, usually timber, steel or concrete. It should have a minimum bearing if 150mm to surrounding material.
What is a cavity tray?
A type of DPC whish is installed across cavities to catch moisture that is within the cavity and allows it a path out of weep vents (installed every 450mm), so water does not sit on the internal leaf and potentially penetrate. They are often installed above openings
What is a cavity closer?
A piece of material that is installed around an opening where a door or window is going to be installed, to ‘close the cavity’ so water cannot enter and improve the thermal resitance of the opening, it is often rigid uPVC.
What is meant by traditional construction?
A linear construction method, from the ground up, most construction done on site.
What is the RIBA plan of work?
It organises the process if briefing, designing, constructing and operating building projects into 8 steps (0-7)
- Strategic definition
- Preparation and Brief
- Concept Design
- Spatial Coordination
- Technical Design
- Manufacturing and Construction
0-2 are often one stage of preperstion
3-4 are drawings options
5 is on site
6 is handover to the client
7 is the use of the building
What is a portal frame?
A construction technique where vertical supports are connected to horizontal beams or trusses. They result in large spans and open spaces. A typical barn construction.
Benefits are of the large open spaces, foundations are only needed for each vertical supports
Disadvantage of portal frames are the fire safety and resitance, it is often steel built which can melt during a fire and high costs of maintaining fire resistant coatings.
What is procurement?
Legal framework of the purchasing of goods and service.
It allows a construction company to maximise their efficiency on each project by having a planned most effective way of purchasing goods and service.
When did DPCs become required by law?
The Public Health Act 1875 introduced the requirement for a DPC, however took some time to come into local byelaws. Some builders were already using DPCs before 1875.
What is a truss roof and advantages and disadvantages? Or why are traditional cut roofs still used?
A truss roof is a structural framework of timbers typically having a W shape to supports or can be boxed to have a roof space.
Advantages include that no internal support is required and large spans can be constructed, relatively cheap and quick to construct.
However a disadvantage is the loss of roof space.
Traditional cut roofs are still used if sites are hard to access or the shape is irregular.