Bed joint reinforcement is a fabricated steel system that comes in a flat ladder or truss design and is added to the mortar between layers of blocks to strengthen masonry panels without thickening the wall. They are flat so they can fit in the mortar or be overlaid and not disrupt the layers of blocks.
Bed joint reinforcement is used for two reasons to help prevent cracking and to help strengthen a masonry panel laterally. This is especially important if a panel has been weakened by a large opening like a door a window.
The masonry panel in the image below is likely to span up and down, as there is no other support around the door and the window. By adding bed joint reinforcement (the second image) you reduce the length of that span and force the load to span horizontally through the strengthened panel.
In structural engineering terms, this is called Orthogonal Ratios, but a contractor may think of it as the ratio of the height of the panel to its width, and so what loads that panel could resist – how strong it would be.
At SWJ Consulting we use digital software to assess the strength of the masonry panels to decide if bed joint reinforcement is enough to sufficiently strengthen it, given the size of the windows and doors and from this decide if stronger concrete blocks are needed or if a wind post is required. You can read more about SWJ’s process of avoiding the use of wind posts here.
Our process to assess whether bed joint reinforcement or even wind posts are necessary, came about because we anticipated from initial drawings for a housing developer that the walls were not strong enough to resist lateral loads. Knowing that if we designed wind posts the client’s question would be ‘can’t we just use stronger blocks’ we agreed to use our assessment process for the 212 houses in the initial stages so that we wouldn’t have to spend time revisiting this issue.
The use of bed joint reinforcement is becoming more common as the trend and demand for larger windows and doors increase. We hear clients say they’ve not needed this before, but they may not have had to work with larger windows before, or there were other supporting factors like a buttressing wall that provided the strength needed.
If you are concerned about bed joint reinforcement in your projects or are looking to value engineer an existing design for developer-led housing, please do give us a call on 01993 225085 or email email@example.com and we can take a look and talk you through your options.