Site search

you can join words with quotes eg. "solar collectors"



Brick

The green credentials for brick walls vary, with three main factors:

  • the embodied energy  depends on what sort of bricks are used
  • the environmental policy of the manufacturer
  • the effect on the wall design

The embodied energy of bricks can vary from 0.7 MJ/Kg for Limestone bricks to 8.2 MJ/Kg for facing bricks. This compares with 0.99 MJ/Kg for normal concrete. It is however usually difficult to ascertain what any particular type of brick rates at. Flettons use the least energy in manufacture with soft mud/stocks using the most and ordinary clay bricks being intermediate

TRADA did some research which compared the embodied energy in timber frame walls with lightweight concrete block (at about 3.5 MJ/Kg)

Timber frame wall – 7,450kWh

Lightweight Concrete Block Wall – 12,816kWh

So since lightweight concrete blockwork has about half the embodied energy of the least energy intensive brickwork then a brick wall might contain between 3.5 and 40 times as much embodied energy. Very rough figures but it gives an idea. The Scottish company Errol Bricks and Ibstock both make unfired bricks which have very low embodied energy. Encos are just starting to do Encobricks and Encoslips which are carbon neutral.

The environmental policy of the manufacturer will determine the CO2 production per tonne of bricks, how much pollution is caused in and around the brickworks (which are usually close to where the clay is mined) and how much wastage is created. The history of pollution from brickworks is lamentable and most of them have a long way to go in terms of improvement. For instance, check this recent environmental report from Ibstock who claim to be one of the leaders in cleaning up their act.

It’s hardly trailblazing stuff but at least fairly honest. Brickworks have traditionally been very inefficient in terms of energy, have been emitters of fluorides and other halogen gasses (which are now controlled) and have been responsible for leaving large areas of countryside in an ugly and degraded state. This latter is mainly a result of large rectangular lagoons where the clay has been mined. Unlike gravel pits which have often produced quite interesting and beautiful wetlands which are useful for recreation and wildlife, clay lagoons tend to be a bit of an eyesore and not very good at supporting a wide biodiversity. Before settling on a manufacturer, try to find out about their environmental track record. This goes for clay roof tile manufacturers as well.

The effect on wall design is to do with the total thickness of walls once they have a fair degree of insulation. Using a brick outer skin rules out using the more ecologically sound insulations such as Warmcel, cork or wool unless there is also a cavity between the brick and the insulation. This is because of the possibility of condensation on the inner surface of the brickwork damaging the insulation. The cavity adds another 25 – 50 mm. to the wall thickness. Achieving Passivhaus standard by packing 300mm of insulation into a traditional brick and block wall produces a total thickness of about 550mm which is so thick that windows become less effective in terms of view and daylight and it actually takes up a great deal of footprint on the ground, which is expensive in terms of buildable space.

Compared with much of mainland Europe the UK has been fearful of modern design and this has led to a rejection of anything that is not brick or stone in appearance. Especially timber and composite boards, which are more ecologically sound and can provide a less space wasting rain screen, have been slow to gain popularity. Of course brick manufacturers have been at the forefront of advertising the supposed benefits of their product. There is a slight wind of change at the moment and most architects designing houses are only too willing to get away from boring old brickwork.

Brick sizes

The standard size for modern bricks is 215 x 65 mm. and a 10mm joint is used. This then coordinates with blockwork. The standard block size is 440 x 215  so if you include the joints then a block length is the same as two brick lengths and a block height is the height of three bricks. Also this means that a block set on its end is equal to 6 bricks in height and a brick on end is the same height as a block, This means less cutting of blocks and allows wall ties to coordinate properly. There are on line ready reckoners by companies such as Ibstock to work out brickwork dimensions and configurations.

Building regulations

Structure

The Building Regulations part A covers the structure of a building. This Approved Document goes into a lot of detail for traditional masonry buildings but almost none for timber frame, steel frame, earth building SIPs etc. For these you will need to consult a structural engineer (while SIPs structures are usually handled by the manufacturer)

Fire safety

With most forms of construction there will be implications concerning fire safety. These are covered in the Building Regulations and you can see examples of how to conform with these in Part B (Fire Safety)

Site preparation and resistance to contaminants

This section,  Part C, covers site remediation along with protection from nasties which might affect the construction and occupants such as damp, rain, radon etc. There is an abridged version of the Approved Document specially for houses.

 

Books

NHBC Technical Guides  free on line

3 comments to Brick

Leave a Reply

You can use these HTML tags

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

  

  

What is 6 + 6 ?
Please leave these two fields as-is:
IMPORTANT! To be able to proceed, you need to solve the simple calculation above. (so we know that you are a human) :-)