Investigating Foundations Click to expand
Some eight years back I moved to the Netherlands with my job and full of youthful enthusiasm set about buying a house.
Unfortunately one little tiny teeny thing escaped me… the value of having a surveyor check that the place I was going to buy was structurally sound!
So here we are in 2012 facing at the very least a major renovation and with the possibility of needing the foundations underpinning.
Being an engineer I like to tackle the problems from the root upwards so the foundations are the obvious first place to start. After visiting the local archive office it turned out I was unable to find any drawings or other information about the actual foundations of the house other than that they were wooden poles.
Luckily I did find a company (wareco.nl) who would, for an exorbitant fee, come and investigate the state of the foundations.
Last week a man rang my bel at 7:45am… he was here to begin digging a whole in front of my house to expose the foundations.
Well, unfortunately at that time of the morning almost no one had left for work so, with this being a narrow street, there were cars and vans parked all across the front of the place… work would have to wait.
By 8am said man was getting agitated about the slipping schedule so I began to ring on doorbells and ‘meet’ the neighbours. None of whom seemed overly happy to have a rumbling digger just outside their window that early in the morning. On the other hand they were really helpful and wanted to chat about the works and their experiences of foundations.
Often I hear people around saying that the Dutch are not friendly and won’t talk or help but I’m just not finding that to be the case.
Anyway, it worked, 20 minutes later we had cleared 5 parking spaces and we could begin digging. Of course, this being holland, it had begun to rain in earnest again so it wasn’t exactly an ideal environment to be digging holes in the street so when I say we… I mean the two contractors began digging whilst I cowered in the doorway staying dry. Ah, so that is the benefit of paying someone else to do the work
Haarlem appears to be built on sand over a thin layer of clay, a layer of peat, and then yet more sand. And it’s below sea level. What a wonderful spot to try and build houses!
To get around the lack of solid ground the builders sank long wooden poles deep into the ground until they found firmer earth (I’m told by a Dutchman that they don’t actually reach the bedrock, just dense enough earth to be stable) and then built on top of.
Well, when our digging man had the hole deep enough that he couldn’t see out anymore he finally reach the foundation poles… they stop 1.8m below the surface.
On top of the poles a long wooden beam is laid and on top of that the walls are built. That’s an awful lot of wall that is underground… must have been an impressive feat for the men building this back at the turn of the 20th century (1901 to be precise).
A bit more digging and he was able to clear the earth from under my wall and put his arms all the way around each of the poles. So once again the front of my house was indeed standing on nothing but the poles.
It appears that there are four poles under the front wall and four under the back wall and a couple (somewhere between two and four… the man wasn’t sure) under each of the side walls.
Once they had exposed 3 of the poles 2 more guys turned up to do the investigation. The first shocker was that one of them was wearing clogs! Amazing… I never really believed that people actually used them until now.
OK, so they punched a bunch of holes in the wood with a spring loaded bar and measured how deep it penetrated, they took lots of photos and measurements, and then they took samples. I was shocked to see how much wood they cut away (a big chunk chiselled off and a core sample from each of the poles). And that was it. They take the samples back to the lab for analysis and send me a report in a few weeks time.
The hole was quickly filled back in and by 3pm it was all over. Obviously I took lots of pictures and you can see more of them and in larger size over in my House Foundations Gallery.