For contemporary log cabins, log homes and any other structure that is built to last long-term, a good foundation is essential. Eurodita delivers our log structures flat packed in most cases and we leave the question of foundation and assembly to our trusted partners. It’s them that make the choice, or the contractor they hire to put together log homes their customers have chosen. However, the foundation is an important question and in this blog post, we would like to share our insights and industry advice on what kind of foundation is essential for log houses.
Basics about the foundation
There are two types of engineers that work with foundation before and while it’s being poured. The first one is the geotechnical engineer, who makes sure that the foundation will have an adequate load capacity depending the soil type that will be supporting it. The second one is the structural engineer, who is responsible for the structural design of the footing.
These two people, and the entire design concept itself, are concerned about the foundation settlement and bearing capacity. There are two types of settlements to be concerned about in this scenario: the total settlement and differential settlement. Differential settlement means that a part of the foundation will settle more than the other part. This can cause problems to the whole structure that the foundation is meant to support. The soil may cause problems too, like clay-rich ones and therefore need to be taken into consideration.
For log homes, the usual, industry standard recommendation is to have at least two feet of distance between the ground and the first planks. This helps to protect the wood from splash back, mud, snow and hard rains. If your customer is planning to have their log house built in an area with high snow fall in the winter, they may need to consider extending this protective distance. It can be done by adding rock or other cladding material on the lower portion of the building.
Pouring the right materials
Just like in classic construction, foundations for bespoke timber houses are crafted as follows: using removable steel forms while reinforcing the steel bar within the walls, the concrete is poured. The forms are removed only after the concrete has cured.
Concrete and cement are not interchangeable terms. Concrete is a mix of cement powder, sand and gravel, sometimes crushed stone and water. The larger percentage of concrete is in the cement mix, the denser, stronger and higher-quality it is. The compression strength of the concrete is measured using the PSI index. It indicates the resistance to downward force in pounds per square inch, usually after 28 days of curing. There are ready-made concrete mixes on shelves and the higher their PSI index, the more they will cost. However, the truly good and reliable contractors that put together log homes and lay the foundation are not afraid to use more expensive and higher PSI rating cement mix.
Depending on the local environment your customer is planning to build the log house on and its soil consistency, 3000 PSI is usually used for concrete walls and footings, while 3500 PSI is more often used for flat work. A truly good contractor will use a cement mix from 4000 PSI rating and higher for something like a full log house. Most 4000 PSI mixes are of such high quality that if properly placed and finished, they will actually reach 4500-5000 PSI. This is largely due to the ready-mix suppliers, who tend to over-engineer their mixes to make up for the environmental and workmanship issues.
Final conclusions
To summarise, the best way to build a lasting, problem-free log house foundation is to find the right people and buy proper materials. If you are a contractor as well as a bespoke log home supplier, you probably already know the challenges that lay ahead with the foundation. However, if you’re the partner who is looking to either hire a contractor, or recommend one, make sure their engineers have a good reputation, the materials they buy are of high quality and the reviews and ratings of their companies are high. When it comes to servicing our partners, we never settle for anything but the best we can do. We can only hope for the same philosophy from our partners towards their own clients.