How to make formwork for the future foundation of the house

Formwork materials

Form­work can be cre­at­ed from almost every­thing that is avail­able. Most often it is made of wood­en shields or ordi­nary boards. More­over, the lat­ter can be used both edged and unedged. Recent­ly, plas­tic form­work is being installed more and more often. It has a low cost. Anoth­er option is sheets of mois­ture resis­tant or ordi­nary ply­wood.

Boards are used to strength­en the entire struc­ture, as well as to con­nect ply­wood sheets. Spac­ers are installed where it is nec­es­sary to align a sin­gle form­work line. The more such spac­ers, the bet­ter the form­work will with­stand the pres­sure of con­crete.

Formwork types

There are only two types of form­work: fixed and remov­able. The first type can only be used once. After all, after the con­crete hard­ens, the form­work turns into a func­tion­al unit of the fin­ished sur­face.

Form­work of the sec­ond type can be used many times, since after the con­crete solu­tion has hard­ened, the form­work is dis­man­tled. As a result, con­struc­tion work becomes cheap­er.

Fixed

This form­work is pre­fab­ri­cat­ed. As a rule, it con­sists of poly­styrene foam blocks or plates con­nect­ed by jumpers and hav­ing lock­ing grooves. This ensures the reli­a­bil­i­ty of the form­work. The plates them­selves are quite light — they weigh no more than 1.5 kg. Their inner sur­face is porous, which pro­vides bet­ter adhe­sion to con­crete.

This is an effi­cient design that cre­ates the desired shape. As a result, it pro­vides:

• pro­tec­tion against fun­gus and the envi­ron­ment;
• ther­mal insu­la­tion and water­proof­ing.

Removable

Remov­able form­work can be assem­bled from dif­fer­ent mate­ri­als.

• Shields. Such form­work stands out among oth­ers with its low cost.
• Plas­tic. Poly­mer pan­els are used for form­work, and some­times fiber­glass is also used. Shields are rein­forced with a met­al frame.
• Chip­board with met­al frame. The mate­r­i­al itself makes it easy to choose the right size of the struc­ture.
• Cut­ting board. From it you can assem­ble shields of var­i­ous sizes.

This sup­port sys­tem is quite easy to mount. How­ev­er, it is impor­tant to fol­low the sequence of actions. First you need to mark the place of work, dig a trench or pit to the base of the pro­posed foun­da­tion. Then it is nec­es­sary to car­ry out the final mark­ing and mount the rein­forc­ing cage. After that, you can pro­ceed to the instal­la­tion of the form­work itself.

Shields of a giv­en size are assem­bled from ply­wood or edged boards. Then a lay­er of poly­eth­yl­ene is attached to the inside of each shield or used machine oil is applied. If this is not done, then dur­ing the dry­ing process, the con­crete mor­tar will seize with ply­wood or boards, and they must be cleaned for reuse.

To main­tain the cor­rect geom­e­try of the foun­da­tion, it is rec­om­mend­ed to pull the cord and install blocks or shields on it.

The walls of the remov­able struc­ture are fixed with wood­en bars. In addi­tion, weld­ing can be used to unfas­ten the form­work. To do this, depend­ing on the diam­e­ter of the rein­force­ment, par­al­lel holes with a diam­e­ter of 8 to 10 mm are drilled in wood­en shields. Rein­force­ment is insert­ed into them and anoth­er piece of rein­force­ment is weld­ed per­pen­dic­u­lar to it, which fits snug­ly against the form­work shield. Thus, a weld­ed T‑shape should be obtained from dif­fer­ent sides of the form­work, which will hold the pres­sure of the con­crete mix.

Con­crete from mix­ers should be poured even­ly into the pre­pared form­work. It is unac­cept­able to pour it in one place. At the same time, it is nec­es­sary to strict­ly mon­i­tor the behav­ior of the form­work: if you notice that it is burst­ing, pour­ing should be stopped, and the site should be strength­ened. Dis­man­tling of the form­work is car­ried out on the sec­ond or third day after pour­ing.

The arti­cle was pub­lished in the jour­nal “Advice of Pro­fes­sion­als” No. 3 (2019). You can sub­scribe to the print­ed ver­sion of the pub­li­ca­tion.