Every day it is more common for our clients to decide to modify the distribution of their home in a reform to adapt it to your tastes or needs. Homes tend to be more open spaces, without as many rooms and with kitchens attached to the living room. To get a renovated home with these criteria, the distribution of the old home must be modified. These modifications usually mean the decision to pull or “move” a partition of the house and before making this decision, due to its importance, several aspects must be taken into account.
In this article we will make a simple approach to the aspects that may be most important.
Is it a structural wall?
The first factor to consider is to make sure that the partition is not really part of the structure of the building. This is not always easy to define since it is possible that, with the passage of time, that distribution wall has settled. To compensate for the deflection of other elements of the structure, sometimes non-structural elements can be loaded.
So be careful! It could be that some of the partitions have become load-bearing walls
To get an idea of which walls we can eliminate and which we cannot, and although a professional should always assess it, you can establish a quick criterion. If the wall is more than 40 centimeters wide, it is likely a load-bearing wall and therefore part of the building structure. Likewise, if its thickness is less than 10 cm, it is likely that the wall is a distribution wall and therefore can “move” without affecting the structure of the building. This, of course, is an assessment that must be made by an expert since it is possible that in many cases these conditions are not met.
Whenever works are carried out, the advice of an architect or a surveyor should be sought who can verify, through the building plans and a visit to the site, what is the structural system of the building and the function of those walls that we want to modify.
In the cases in which we finally find a structural wall, we can carry out the reform by building a shoring , but we must bear in mind that the process and the costs of the reform will be longer and more expensive .
If it is a partition and it contains facilities?
Care must be taken when removing partitions, especially when the horizontal structure (the ceilings) are made of old wooden joists since this type of structure deforms a lot over time, the joists are arching they tend to arch, arrow, little by little . When this happens, the ceiling may come to rest on the partitions and when a partition is demolished, the partition of the upper neighbor will crack and split a tile or some other finishing element.
Once it is ruled out that our partition to be demolished has not come into charge, then we must monitor the facilities that run through it.
In the cases in which we verify that our wall is not part of the building’s structure, before we can make the hole or “throw” the partition, we must check that the conduits for the facilities of our home do not run inside the partition. . It is common to find that inside the partitions cables of the electrical system, pipes of the plumbing system have been hidden and / or in the worst case, we can find the gas conduit of our home.
The contracted technician must be in charge of checking, with the updated building plans, that inside the partition that we want to demolish there are no installation steps. This check should be done before starting to carry out the work for the change of distribution since, if we “throw” a partition with a pipe or cable inside, it can not only result in costly damages, but it can also be very dangerous.
In cases where installation steps are finally found inside the partition, the renovations can be carried out anyway. The affected supplies must be cut off and the pipes or cables must be channeled so that they run through other areas of the house. Due to the danger posed by facilities in poor condition (gas leaks, water leaks, electrical contacts), this process must be carried out by qualified personnel.
The wall is structural and we must carry out a shoring. What is a felling?
A shoring is the deflection of loads that is carried out, normally by means of a beam, to modify the original descent of loads of the building. Normally in the execution of a felling we will carry out two felling processes: the provisional felling with struts and mechinales and pins which is a temporary construction that is installed to reinforce the structure of a building during a modification of this; finally we will carry out the definitive felling in which the structure will remain “open” and in adequate safety conditions.
There are multiple variations of shoring, depending on; the loads to which the wall is subjected, the thickness of the wall, the distribution of the rest of the structural elements, the size of the hole that we want to open and many other aspects that the contracted technician must take into account when defining the shoring system.
Dethroat felling on both sides of the wall
This type of load-bearing wall shoring is used for short spans (shoring distances) and low loads as it involves a high risk if done without a temporary shoring.
Lowering with retaining of the wall by means of a lower beam
Next we explain an example of a felling made by opening a hole in a structural wall inside a house. This type of shoring is based on placing a beam that is normally fully embedded in the thickness of the wall. This implies that a complete provisional felling must be carried out. It is suitable for large lights
Falling with confinement of the wall
a1.This type of load-bearing wall felling is characterized by the fact that we do not have to temporarily lower the wall and is the one that provides greater safety conditions if the masons in charge are not especially skilled in the execution of this type of works . They are supports that are generally appropriate to support low loads. A beam is placed on both sides and they are joined with connectors that are generally epoxy threaded bars. In the upper figure is the first schematic (a1)
c. This is the safest type of felling and the one suitable for carrying out large spans and heavy loads. It must be carried out by professionals specialized in this type of operation.
The steps to be followed by the client
1. Previous studies
Once the aforementioned aspects have been broadly studied, a technical project must be carried out to define the structural dimensioning and the construction procedure to be followed.
2. Project
The project will contain a study of pre-existing loads of the building, paying special attention to the wall and foundation where it will intervene and, above all, the singular or unexpected modifications that may exist in upper and lower floors.
A study of modified loads will then be carried out in which it will be verified that the deviation of loads on the wall does not produce situations that compromise safety on lower floors and foundations.
Finally, the new structure will be dimensioned based on the structural regulations, the CTE of actions and normally the CTE of metallic structure. Checking the resistance to breaking states and deformation limitation state, which are the most limiting:
In the structural calculation, the deformation of the new beams is limited to 1/500 or 1/1000 of the span. This means that if we have a 2 meter beam it cannot have a maximum deflection of more than 2 mm !!
And that after considering some loads with the safety coefficients and with the reduction coefficients of the resistances of the materials. Check here the content that a project should have.
Once the project is finished, we can obtain the building license (remember that according to article 128 of the metropolitan ordinances we must notify the neighbors about the existence and the possibility that they have to consult the project)
3. Construction
Since it is an operation, although simple, with a lot of risk in the work, all the steps of the construction process must be carefully planned and executed. It is convenient that the masons we choose have experience in this type of work and those in charge of welding the structural profiles know how to weld: that they can make continuous beads, of the thickness specified in the project and also that the weld beads are clean and without pores.
Example of felling. Double profiles on concrete blocks.
Extract from the plans of previous studies of the project
Section and plan of the area to be demolished and elements to be built
Project definition details extract
The type of felling contemplated in this project is that of felling with wall confinement. We have done it in the municipality of Terrassa in the context of a comprehensive reform of an attic. Below you can see an elevation detail of the shoring composite beam:
Below you can see a sectional detail of the shoring composite beam:
Extract of details of the construction procedure of the project
STEP 1. The area of action is defined. In the case of our concrete there is an opening in the left area that will be eliminated (a wall marked in red will be built in the drawing). To avoid transferring actions to the lower floor, we will lower this new wall below, in such a way that the decrease in loads is the same. Remove the wall cladding layer (usually plaster) and carry out tastings to ensure that the constructive reality corresponds to the project (if it has not been done previously. Disassemble the false ceiling next to the wall and dismantle the pavement next to the wall. The objective is to expose the masonry wall that is in the area of action. In this way we will be able to see at which points the slab joists rest on the wall. Marking and dimensional stakeout of the shoring is carried out.
STEP 2. A shoring of the upper floor is made with inclined struts to carry the loads in the lower part towards the base of the wall, in this way we ensure that the descent of the building loads will not be interrupted during the intervention works. Immediately after the placement of the props, small holes are made to build the concrete blocks where the beams will rest on the wall.
STEP 3. A metal profile is placed on the concrete blocks, which will act as a capital to transfer the load from the two beams on both sides of the wall to the concrete block. The areas of the metal profiles ( the beams ) that rest on the concrete blocks are filled with mortar without shrinkage.
STEP 4. With the provisional structure ( props ) and the metal profiles in place and fixed, the wall is demolished.
STEP 5. After the whole process, the hole is finished and it only remains to re-apply a coating layer on the wall and replace the flooring and false ceiling that were removed in step 1. As you can see, in this type of felling the last step is the demolition of the wall (this does not happen in many other types) and this makes it one of the safest procedures.
In this image we can see the final result of the example that we have explained. The concrete blocks are not noticeable because they are plastered.
Conclusions.
It is very important that this process must be done by qualified personnel and each specific case must be studied carefully to ensure that we comply with current regulations and the necessary safety conditions.
If you are interested in shoring a structural wall or removing a load-bearing wall contact with KAITEK ARQUITECTURA, we will accompany you and we will work to make it an easy and agile process for you.
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