The cause of bowing walls in many old buildings may well be due to the fact that there is no mechanical connection between the floor and ceiling joists and the masonry. The traditional methods of connection has been to rely on friction due to gravity. When this frictional resistance is released, due to movement over the years within the timbers or masonry, it can leave a freestanding wall of considerable height that is very susceptible to bowing.
The problem of bowing walls has been addressed in the past by the use of S or X ties (hoop irons) bonded right through the building with bars to connect the front and read walls or the two side walls together. The BowFix uses the same principles as this proven but unsightly method of restraint for bowing walls. The advantage of the BowFix is that it can be installed remedially and externally and uses the existing structural members to provide the necessary stability.
The current method of standard repair is to introduce a galvanised strap tying the floor to the wall. This involves removing furniture, carpets, skirtings and floorboards, the chasing out of plaster, the fixing with plugs and screws or nails and the subsequent making good. Therefore, although the product itself is very cheap the disruption involves during the installation makes this a very expensive option which relies on the holding capacity of plastic plugs and screws.
The BowFix system of wall restraint from Hertfordshire based Helix Fixings is available in 8mm material. Installation is performed from outside the building through a 12mm hole in the building fabric. It must be emphasised that a check must be made for any services that may run through the floor/ceiling cavity. It is quite common for wiring to be present and is certainly not unknown to have water pipes for the heating system or even a mains water pipe in this location. It is recommended that checks are made in this area with the use of a borescope.
The connection to the wall is either made into the second floor joist, if they run parallel with the wall, or into the ends of the floor joists if they run into the wall. A proof test of the connection into the timber can be made immediately after installation using a Load Test Unit. The BowFix is available in 8mm helical stainless steel.
Locate and mark the positions of joists on the external wall. Drill a clearance hole (normally 12mm) through the masonry in line with the centre of the joist and continue to drill the hole through the first joist. Blow out the hole to clear any dust and debris.
Insert BoxFix into the driving tool, push the tool and tie into the drilled hole and using the SDS hammer drill, drive the BoxFix into the second floor joist for a minimum depth of 50mm.
Remove the BoxFix drive tool from the hole. Note - at this stage a tensile test may be performed to prove the fixing of the tie.
HeliResin or HeliGrout 25 is used to bond the BowFix to the wall to complete the installation. Make good at surface of all holes and leave ready for any decorations.
Call Helix Fixings to order Super Spiro BowFix
Call us to speak about the Super Spiro BowFix solution that we supply for construction projects across the UK and the US from our base in Hertfordshire