The Cottage Problem
The front wall of our cottage leans out from just above the top of the plinth to the wall plate. Overall about 10 – 11 degree lean in the wall between the window and the door. Its a timber frame – ‘H’ frame – with wattle and daub infills. Its a listed building. Suggest you scroll through the pictures included below to see the problem.
Been living here for 10 years now and the front wall is in the pretty much same state as when we moved in, but some more cracks have appeared over the last winter in the concrete(!) render applied by previous owners. Its not possible to tell if its just the render or more … but as you will see from the lean of the wall and window we cant take the risk of just leaving it. When purchasing surveyors said it was stable though fragile and leave as is often the best policy in these situation where such buildings can cope with such lean for centuries. But recent inspection by engineer reports we should strap to restrain roof spread, find and fix failed timbers and implement some permanent additional support v roof spread, asap as any more inches of spread would be v bad. Engineer also identified decayed wall plate immediately under upstairs window as in need of replcement.
Its not an even lean across the whole front: the right hand side of the window frame is the epi centre of the move – on the inside of the wall at this point, just above the plinth the wall has been broken (see pics above and below) . The wall looks quite normal on the left of the window but from there moves inward from the base to most recessed at the right hand side of the window and then moves back into line at the left of the door. / \
At the most the wall is at maybe 11 degrees as a result. It looks to me like the post has broken near the brick plinth and when I removed some of the internal plaster several years ago, I could see some work was done on the sole plate including use of flitch plate. The plate looks like it has sharp edges to me and if a post were inserted into it, which judging by its position I would expect it must be, could see that it would snap a post on which a leaning force was applied. Alternatively a rafter has come loose from ridge and caused connected post to move out at top and in at bottom. Alternatively the very heavy window frame has caused the post to fail/break. Finally sole plate might be rotten and cause for of post to dislodge and ‘float’. Which of all of these would be cause v effect is debateable but the Engineer reports that the structure or the building isn’t effective v roof spread forces: the collar tie is too high. We considered knee bracing each stud but the 1st floor joists are under spec at only 5 inches and replacing them all with say 8 inch rafter would be a lot of work/impact on heritage timbers as floor and ceiling would need to repositioned too.
The yellow line indicates bottom corner of ground floor window.
This view taken from the inside show how far the window frame and plinth have parted ways on the left of the frame (from the inside).
Repair … …
Obviously the wall (wattle and daub) needs to be stripped to see exactly what has failed and repair. But the engineer points to roof spread as the underlying cause of the problem, due to poor original design, and has recommended we add additional support against further roof-spread as the tie collar is in the top 3rd of the roof and its an H frame building – so roof spread inevitable fm the design. This seems an elegant solution – wall plate at front is connected to wall plate at back by a tie frame running alongside the floorboards but with raised arms at either end to meet the wall plate (H frame). The engineer also suggest another tie beam on the party wall.
So as well as stripping down all the infills (for reuse of course), replacing and repositioning any defective timbers we will need a steel fabricator to make and help place the metal tie frames.
Here are some diagrams showing the cottage and then the proposed additional ties.
Plan of Attack
The initial tranche of work i am talking with the conservation officer about is to strap the walls to prevent further roof spread ASAP. This involves connecting the front wall plate and rear wall plate with 5 tonne straps and then supporting the front wall plate with props. To do this I will need to remove (and store for reuse) some internal plastering to see the structure of the wall plate and supporting studs (in order to place straps and props safely (so not putting a hole through a post or strapping a 3 inch minor support instead of the 5 + inch studs!).
Once we have strapped and supported the walls temporarily we will need to convert and extend garden sheds to give some temporary accomodation as well as additional storage that we can camp in when we embark on the repair work.
Once we have that we can remove the wattle and daub infills fm the front wall as well as some of the ceilings around the collar tie, inspect the timer frame in detail to see what has actually failed and why, repair posts/braces/rafters as necessary and, assuming planning permission is given, install some 3 new metal ties to help the wall plates resist rood spread going forward. I hope to employ professionals to do the structural timber work but plan to do the wattle and daub infill work, both stripping down and then redoing once structural work complete (been on Orchard Barn courses for wattle and daub and timber framing).