Foundation is a very crucial step of a house build. Many things have to go right. This part of the journey was like driving in a super slow moving traffic with many traffic jams.
My previous articles at
- My house build journey : Location
- My house build journey : Design
- My house build journey : Building permit
- My house build journey : Technical Consultation
- My house build journey : Stalled by Bank Bureaucracy
- My house build journey: Start Message
There were many steps and checks involved in the foundation process.
Rough demarcation (Grovustakning):
Rough demarcation is the first step and is usually carried out by the municipality or by a certified GeoTechnical company on behalf of the municipality. The rough demarcation is done according to the situation plan. The situation plan is a drawing which shows where exactly on the site map the building will be placed. The data from the situation plan along with some geo measurement instruments were used for the rough demarcation. A blue paint along with a stick was put up at the four corners.
GeoTechnical Assessment with Shaft Bottom inspection (SchaktBotten Besiktning)
Shaft Bottom inspection is carried out as part of the protocol for any constructions. Normally they don’t need to be supplemented with an additional geotechnical assessment. In my case, I believe it was due to the geotechnical report that I got from the municipality which mentioned that there were some loose soil in few places which were removed and filled back as part of the site preparation. This was kind of like cross verification step. Thinking about it, I am not exactly sure why this responsibility was passed to the home owner. Anyways I had a Geotechnical company who did the inspection.
Two sample points were dug up to about 1–1.2m deep. The soil pressure was measured using a metal stick like instrument. The results were found to be satisfactory for the construction of the small (1–2 floor) house småhus.
Fine demarcation (Finustakning)
Fine demarcation is carried out by the same company who did the rough demarcation. In this step, a corner profile is created out of the sticks and threads are run across. The intersection point of these threads are where the edge of the foundation is suppose to align and also the foundation slab finished floor (Färdig grund ) is supposed to align. The finished floor height (Färdig grund höjd) is 57.6 (If you remember, I had this updated during the Technical consultation meeting). The perimeter of the foundation is usually less than the perimeter of the house. The width of the foundation is 9.9m and length of the foundation is 17.9m
Drainage surface (Dränering underlag)
After the required amount of soil was excavated, a geo textile cloth was laid. A first layer of coarse macadam was laid and packed using a compacting machine (packnings maskin).
A second layer of finer macadam was laid and compacted on top of coarser macadam.
Draining pipes are also laid all around the foundation. The pipes are covered in the macadam and geotextil cloth is wrapped around it. The pipes have small holes that let water in.
The draining pipes also are connected to a drainage well and then goes to the municipality drainage pipes. Every site has a drainage well.
All these methods help keep the water and moisture away from the foundation.
A formwork was built aligning the pink threads around the perimeter. Insulation elements made of cellular plastic (EPS) were laid out. They are available in different densities. The edges (where the foundation beams were to be cast) have a density of S300 and the other ones in the middle have S100 density. The total insulation is 400mm (300mm is normally used). I went a bit extra with insulation.
Water inlet, sewage pipes, Electricity, Fiber pipes
Some contractors(as I could see the neighbours construction) lay out these pipes before beginning laying any insulation elements. In my case, the contractor did these in just before finish laying the last piece of insulation elements. I have all the wet rooms mostly concentrated on the left side of the house. Electricity (yellow pipe) and Fiber( green pipe) were also embedded.
Underfloor heating cables
After the insulation elements were fully laid, underfloor heating(blue) cables were laid. The plastic covered thing in the image is the distributor (golvvärme fördelare). A pressure test is done after laying the underfloor heating cables.
Steel reinforcements were built according to the construction drawings. The edges beams have about 500mmx500mmx500mm reinforcement mesh. The places where load bearing walls will come up, have extra reinforcement with 200mm concrete while the remaining area will be 100mm concrete.
It is usually at this stage that the Control inspector (Kontrollansvarig) is suppose to visit according to the control plan. He visited a few days earlier when the reinforcement was not fully complete but he didn’t see any deviations from the protocol check and was ok. I also had an additional inspection done by a third party inspector (Besiktningsman).
Traffic Jam 1: The foundation contractor thought that geo technical assessment was not needed and was about to proceed with the next stage of work. I had to rush to the site to explain him but he was still not convinced (probably a bias that he has done a lot of foundations and I probably had misunderstood). I had to call the Geotechnical assessment company and he was able to explain to the foundation contractor on why this was needed and it was expected by the municipality. Later we fixed a date and geotechnical assessment was carried out.
Traffic Jam 2: The insulations elements were out of stock and also there were delays due COVID-19. We lost quite some time there.
Traffic Jam 3: The foundation contractor found a cold bridge problem (A bit late but better late that never). We had to go back to the drawing board and get updated drawings. The architects were also busy but we managed to get some sketches and updates were done. The cold bridge was at the east site where I have this place to sit out.
We had to make sure to break the heat loss from inside to the outside. As a solution, a break was created with an additional insulation element and 2 layers of asphalt paper with this U shape.
Traffic Jam 4: The initial company from which we were suppose to get the underfloor heating pipes had no stock and we had to switch to another company. It was wrongly delivered to a different address and were stolen. The company had to resend the pipes. Some more time lost there.
Traffic Jam 5: While the foundation work was going on, the CLT contractor was working on a production model design. They found a problem with fire rating document. According to the interpretation of the fire rating document, there was a potential increase in the internal load bearing wall thickness to about 160mm. This would have been a big problem because all the underfloor heating cables were put , the drains and pipes were marked according to the measurements. This change in thickness would mean redoing all that stuff. I had to get in touch with the architect (who did the fire rating document) and the CLT contractor discussed with them. It turned out that the there was a mistake in the fire rating calculations. Everything was ok and we did not have to change any thickness of the walls. This also caused some confusion and delays.
Traffic jam 6: The weather was not that ideal at all. It rained for many days limiting amount of time to work on site.
Traffic jam 7: It was really hard to find an inspection time. The amount of certified inspectors are very few and adding to COVID-19, everybody was more busier. We finally managed to get a slot. The inspector carried out the inspection according to the drawings. He cross verified the measurements asking different questions to the contractor about the materials and taking pictures. He found 2 major problems. The distance between reinforcements were wrong and the other one was again related to the outside sit-out place. That area would be prone to retaining water due to rains etc. We had to go back again to the drawing board and find a solution. The solution was to cast 2cm less concrete and we need to slope that area and fill it with a water proof coating layer later.
Retrospectively, that open sit out area caused unnecessary problems and additional costs. Probably it would have been better to skip it (note for a future self or anyone else intending to do something like this :) ). I could have just cantilevered that part of frame or probably just built it later with some other material or probably just skipped it entirely. About 20sqm of foundation and the frame could have been reduced.
Traffic jam 8: Finding an appropriate day for casting the concrete also took some time as the temperature kept dropping. We wanted to avoid going below 0° C. The concrete was also mixed with some winter based elements that help dry the foundation.
Traffic jam 9: I also believe the foundation contractor delayed few days on his part as well. Probably managing other ongoing work etc.
Finally, the casting was done on Dec 2, 2020. I think it took 2–3 concrete trucks.
It snowed a bit the next day
After few days, the form work was removed.
Position control (Lägeskontroll)
After the casting was done, position check was done. This is sometimes done before casting. In my case it was done after casting. This step is to check if the position, sizes etc matched to how the measurements were done in the Fine demarcation and are according to the situation plan. It is the same company who did the Rough demarcation, Fine demarcation also did the position control. It turned out to be ok and within tolerances. The length of the foundation was off by 10mm and FG height was 57,61 instead of 57,60.
Overall, I am about 70% satisfied with the way it turned out with the foundation contractor. The finishing and the level of detailing could have been better. Hope everything functions fine in future. 🤞
The YouTube video for this part can be found at https://youtu.be/zivNsWUxy3g
The complete channel playlist at My House Build Journey
Instagram account at Villa Shailesh
Given how this whole process has turned out, the CLT frame installation obviously was delayed and will now be assembled in Week 1, 2021. We hope to make it weatherproof within that week or by the consecutive week.
Unfortunately, the response to my extension request was not positive 😔.
“I understand that the situation has changed through the virus outbreak that we got this spring. On the other hand, I can not grant any longer deadlines, but if it is a matter of a few weeks or up to a month, it is of course possible to solve. Get in touch sometime in the new year and we will see where the project stands then.”
Realistically speaking I expect it to take about 3 months more.
The windows are awaiting some last minute finalisations. They have a long delivery time of about 2 months. The roof also needs to be ordered. Trying to figure out if we can reduce some costs with the facade. I have come across another material Cembrit Patina Rough which could provide a brick look. They are lighter, easier to work with and a bit cheaper. But has to be approved by the municipality. 🤞
Let’s see how much progress we can make in January 2021.
Status at the time this article was first published.
Days left for final inspection: 110 days