Why Has Your Wall Cracked? and What Can You Do?

hello i'm roger bisbee from the skill builder channel and i want to talk to you in this whiteboard presentation about cracking up cracks in buildings let's have a look at that a lot of people get very alarmed about cracks in buildings saying oh my house is falling down how's this really fall down generally the odd crack in the building is not going to make it full one of the reasons for that is we've got something that was invented 7 000 years ago which we still use to this day and that is brickwork brickwork bonded so that if there is a crack the load is spread across now what you very often find in old brickwork is you might find a crack in the brickwork which is going down the watercourse along there down there along there down there and along there very very common that kind of thing that's one of the beauties of brickwork is it is kind of accommodating and if you don't make the mortar too strong put a bit of lime in it five sand one cement then if there is any movement in the building let's face it all buildings move at some time if there is any movement it's taken care of by this natural give in the brickwork structure which is a fantastic thing if that happens if you've got an old building if it's built a hundred years ago as much of the london property was it's got sand and lion buildings the worst thing you can do is go poking sand and cement in there a nice strong mix of sand and cement in there thinking that you're going to be sealing that crack up another thing that's not very good to do is put an epoxy resin in there so that you end up sealing that crack up and there are lots of masonry repair kits around which use precisely that idea they use this resin to try and tie the thing together all well and good i've used those myself you need to know why that building's cracking up in the first place and whether it's actually a problem because if it's not a problem there's no point really in putting a straight jacket on it if you put a straight jacket on that if you put a nice strong resin all the way down that crack what you find very often is that the brickwork will just crack next to it and i've seen that time and time again where there is a crack next to the crack if you like the first thing you need to do is find out why that crack is occurring the whole of london is built on clay probably one of the worst conditions that you can build on the problem is with it expands and it contracts according to the moisture so if you get a very wet winter and that clay gets saturated with water you're going to get what they call heave which is the expansion in the clay and it's pushing up and it's pushing on the walls pushing on the floors and it creates a tremendous amount of force in the summer when it dries out if you get a very hot summer and then you've got several weeks or months even without rain then all that clay will crack up and you'll see all these fissures across the ground you know sometimes looks like earthquake and of course what that does is it means that the foundations that are sitting on that clay are suddenly not supported evenly and they will start to crack up to a certain extent this has been going on all these years and it's no big deal they heave in the winter they shrink in the summer the buildings to some extent as i say if they're built with sand and lime they will tolerate a little bit of movement in that way in that case the worst thing you can possibly do is go putting a strong mix of sand cement or resin into that crack because if you do the ground has shrunk away the crack has opened up you fill it up with something really tough like a three to one mix of sand cement and then the winter comes and the heave occurs and what you get is that crack that you had before the brickwork is trying to go back to where it originally was but it can't because you've filled it up so it's going to start pushing the building out and this is what we call ratcheting this is a process by which that crack gets wider and wider because you've filled it up the next year you go back you go oh it's opened up again it's got wider and it carries on getting wider and all the time you're thinking my goodness my building's falling down i need to get it underpinned and if you just left it alone in the first place it would have been fine so if you're going to fill up a crack and i understand why you would want to fill up a crack fill up the crack with the same material that the wall was built from so if it's a sand and lime construction get yourself a bit of hydraulic lime mix it with some sand and fill that crack up the sand if you've got other situations if you've got a building which isn't suffering from heave if it's not built on clay say it's built on sand as mine are something like a drain leaks under the foundations and washes the ground away the ground starts washing away and you find that you've got a crack in the foundations then you get a crack then that is something that you can do with the crack repair kit where you basically chase out the mortar courses you put in the helical tires which are stainless steel twisted bits of bar which go across the crack so you chase out the mortar all the way across here maybe a meter and then you push in the helical bar across there and then you put back a resin and then on the top you put back sander cement so that nobody can see it and if you get a good guy to do the crack repair they match the color of the mortar and you'd never know that it happened so if you've got a crack in the brick they probably replace the bricks and they put in the helical bars to stitch the crack back that's called crack stitching very effective way of dealing with it and i have actually seen buildings up in suffolk where they've actually run this helical bar all the way around the building on several courses just to hold the building together because the whole thing is starting to fall apart so you can do an awful lot in remedial ways the other thing that you used to see on the outside of buildings the old wall tyres piece of metal that they got a bolt through the middle of them if you've got a building like that and you've got the walls starting to belly out they start to drift apart on one end or the other what they do is they put a rod all the way through maybe at floor level going all the way through the joists and then they put the wall ties on there and then they start doing those nuts up and you can even start to pull the building back into shape but if you don't at least you stop it from going any further now that's now done with invisible wall ties so that you don't see it because a lot of people worry about seeing external wall ties i bought a house that had external war ties on it and i thought that's fine there's nothing wrong with it the mortgage company didn't mind it because basically the problem had been solved whatever was happening in that building had now been constrained but another thing that we do now we put in some kind of restraints on the wall we were putting straps on the wall going down the roof and we would put straps in where we've got floor joists going through the building like this we would put a strap in across the floor joists that went into the wall to hold the walls together one of the problems that we got these days is that people want to take all the internal walls out of their house because they had this lovely old house that was a few hundred years old the rooms were all small in those days they didn't want to heat huge spaces but now because we've got central heating and we want lights and air in our buildings and they might take the back end of the house away great bifold doors take all the internal walls away you're sadly left with these great big long flank walls there's nothing restraining them you might have had some chimney breasts going through there at one point what you've done is you've taken all the chimney breast away and you've left that wall unstable very important that when you take anything away in a building this is a golden rule you put back more than you took away in other words you're taking away structural restraint from the chimney breasts put back more structural restraint than you took away that way you can't go wrong the other thing we find is when people put loft conversions on suddenly they're putting an extra load onto that wall and very often when i've done loft conversions they've asked for us to do a little foundation dig where we dig a few holes around the foundation so that the surveyor can come along and see just how far the foundations go down and a lot of the time in old buildings in my house there aren't any foundations it was built brick on earth it's just slightly wider bricks spread of course is there it's just stuck straight down on the sand a lot of people would be alarmed by that but in actual fact it's been there for over 100 years it hasn't moved it hasn't cracked it's unlikely to crack in the future unless there's something like a leaking drain so very important by the way that you go around you just check your drains are working properly but i always say to people go and walk around your house when it's pouring with rain because you learn a lot grab an umbrella walk around the outside of your house and just see what's happening because sometimes you find there's overflowing gutters where the water's just pouring up over it and the first thing you know about it is you suddenly got a crack in the building because you've got a leaking drain or you've just had water pouring down there saturated a bit of ground washing a bit of ground away and it's undermined your foundations or in my case your lack of foundations you also get crap sometimes when you've got a neighbor who starts doing an extension right next to your house they get a bit too greedy and then they start undermining the foundation when i was an emergency plumber got a call and he said i mean can you come out we've gone for a water main back in those days they didn't have the kind of provisions they got now where you could simply screw a coupling on and repair it yourself so he needed my skill my expertise if you like him using a blow lamp and lead to repair the water main i said to him all right i'll come around there and have a look at it all these guys were running around with that crows and boards and i said what's happening and he said just stay there just stay there for a minute i stood there in the back garden and the owner of the house was also standing in the back garden the whole of the back end of the house was part and company with the main bit there was a crack appearing all the way down here and it was moving outwards and you could hear it creaking like the ship's timbers very alarming to watch and the guy who owned the house was also alarmed by it what these guys have done is they were doing some underpinning because there had been a small crack there so they were doing the underpinning taking away sections of the ground pouring in concrete and when that concrete sets you then take it out the bit in between they give you a big schedule for it and the inspector comes and looks but these guys thought oh we can do this whole job in a week rather than two weeks and they dug out a bit more than they should have to uh try and pull the concrete in obviously they overdid it and the house started to move and they ran around and they put in acros all around the outside of the house into the trench on bits of board just to stop this house from moving away so they could pour the concrete basically and underpin it little things like that if you get underpinners in if they're good underpinners they will do the job properly and they will stop that happening that crack opened up that building was like that and they didn't push it back they just left it there filled the crack in straightened the floors back up that was how it is to this day so there's a lot more to say about cracking but that's just a brief overview if you see an internal crack it's very likely to be something like superficial movement a bit of internal shrinkage don't spend sleepless nights worrying about cracks in your buildings if they look like they're starting to get serious get some professional advice they will come around and put little telltales on it and they will monitor the crack over the course of several months to see what's happening if you're going to do a diy job on a crack yourself just bear in mind what i said about not making matters worse i'm roger bisbee i hope you found that brief overview of cracks illuminating and if you've got any crack problems send us some photographs we'd love to see a good crack

Channel: Skill Builder

Views: 657,145

Keywords: wall cracks, crack in wall, drywall repair, cracks in walls, wall crack, cracks in wall, home renovation, how to, crack in wall repair

Id: Fpdb69ccNkI

Length: 11min 53sec (713 seconds)

Published: Wed Mar 02 2022