Page 8 - 01 Building Materials
P. 8
PROFESSIONAL TIPS PROFESSIONAL TIPS
FROST PROTECTION FROST PROTECTION
FREESTANDING WALLS EARTH RETAINING WALLS
Freestanding walls can be subjected Where brickwork is in direct contact
to severe weather conditions. In with retained earth, it is exposed to
order to minimise frost damage ground water which invariably
careful consideration must be paid contains salts.
to the following aspects of design: F2/S2 quality coping with minimum
F2/S2 quality coping with water absorption of 7% To minimise the risk of efflorescence
minimum water absorption of 7%
Class B quality bricks should be on the exposed face of the wall,
used from foundation level to 150mm a waterproof barrier between the
(minimum) above ground level (M12 High bond DPC retained earth and the brickwork
High bond DPC mortar or 1 : 1/4 : 3). This will also act should be provided
as a rigid DPC
The waterproof barrier will also aid in
The main body of the wall should be the minimisation of frost damage
constructed in “F2/S2” quality facing Granular F2/S2 and sulphate attack
bricks (M6 mortar or 1 : 1/2 : 4 1/2) backfill is quality
preferred All other detailing should be in
All copings must be of “F2/S2” for better brick accordance with that stated for
F2/S2 quality and have a water draining a freestanding wall
quality absorption not exceeding 7% abilities Rendering of the wall is not
(M12 mortar or 1 : 1/4 : 3)
brick recommended under any
We recommend that drip channels circumstances
are introduced on all copings to
Class B shed rain clear of the wall face Class B A cement rich M12 mortar (1 : 1/4 : 3
quality quality cement : lime : sand or equivalent)
brick Drip channels should have sharp brick should be used for cappings and
edges and be free from mortar or copings on both freestanding and
other obstruction retaining walls.
Copings should overhang the wall
face by at least 45mm FROST ATTACK
“F1” quality bricks must not be In extreme conditions even frost resistant
used for the main body of the wall, F2 bricks have been known to fail.
cappings or copings on freestanding Where there is a likelihood of long term
walls Protect the saturation during cyclic frost conditions
earth face occurring, it is advisable to choose a
Strip Mortar joints are not impervious to of retaining Weep holes brick of high strength and low water
in outer leaf
foundation moisture. This is resolved by using a walls with a of brickwork absorption as an added precaution.
high bond continuous damp proof continuous Strip It is important to follow the above-
membrane immediately below the membrane foundation mentioned good building practice
Granular backfill is copings, projecting at least 13mm details when constructing walls and
preferred for better beyond the mortar. other vulnerable structures.
draining abilities A flexible DPC should be avoided at Care should always be taken to observe
all times as this will reduce overall relevant design details and current
structural stability. Codes of Practice.
TRUSTED BY TRADES
20 Prices correct at time of print. Prices correct at time of print. 21
