CONSTRUCTION OF A SAFE HOUSE
1. Drawings and permits (or other administrative procedures)
Once you buy your parcel of land in an adequate location, you must design your house. If it is possible, get advice from an engineer or architect for the design of the house and the drawings. You can approach your local municipality to obtain help with your drawings and to find out if your house can also be used for a business. Remember that the construction of your house must be formalized by registering it in your town hall.
Cleaning and leveling the land
Before starting work, clean the ground well. Remove all trash, construction debris, organic material and loose soil.
Organic material is bad for construction.
Page 19 Leveling the land The construction site must be level, and above the drainpipes for your area. To level the site you must cut and fill the ground, so that ultimately it is completely flat at the required level.
Less than 1 meter
More than one meter
Desired finished ground level
Use a ½” diameter transparent hose with a maximum length of 10 m
Use 1.5 m high stakes
Run the level
1. Fill the hose with clean water and verify that there are no bubbles.
2. Place stakes along the perimeter of your site and verify that they are plumb.
3. Use a stake to identify a reference point level such as the level of the street. Mark a height of 1 m above the reference level on this first stake.
4. Using the water level inside the hose, mark the height of the first stake on all the other stakes.
Cut and fill.
After marking all the stakes, measure on each one the distance between the mark and the level of the natural terrain.
Fill and cut the terrain until the distance between the mark and the ground is 1 m.
When the distances measured are greater than 1
When the distances measured are less than 1 m.
To fill the ground, place layers of soil 30 cm thick. Wet each layer with water and compact well with a rammer.
The layout is used to show the position
on the ground where the foundation
of your house will be constructed
Construct several guideposts from
wood stakes on the ground where the foundation of your house will be constructed Construct several guideposts from wood stakes.
Place the guideposts according to the drawing
dimensions so they define the edges of the building footing.
Straight angle (90 degrees)
Locate the center of each footing and extend strings from each end of the guideposts limiting the width of each footing.
Use 3-4-5 triangles to verify that all walls are perpendicular (that is, all corners are right angles).
Use the strings as guides and mark the width of the footing on the ground with chalk or lime.
4. Construction of the Foundation
In the following drawing you can see the minimum require footing dimensions.
30 cm minimum
Slab on grade
Compacted filling ground
For houses up to two stories with bearing walls:
For hard soil like rock and gravel, minimum 40 cm
For sandy soils, minimum 70 cm.
To determine your soil type, go to the next page.
Construct stepped footings when the terrain is sloped.
Hard soils such as rock or gravel are the best foundation soils. Gravel is made up of different size stones and course compact sands. Sometimes it is difficult to excavate these soils with a shovel and you have to use a large drill.
Find out about the footings of nearby houses. If nearby houses have settled under their weight, then your foundation should be wider and deeper than that of your neighbors.
If your soil is not gravel or rock, how can you recognize what type it is?
You can do this simple test.
1. Dig a hole in the ground 1 meter deep and take out a sample of the soil.
2. Place a portion of the soil in a transparent bottle until it is one third full. Add another third of water and one spoonful of salt.
3. Shake the bottle strongly until the mix is uniform.
4. Let the mixture settle for 24 hours.
5. Measure the heiht of sand clay and silt.
Silt clay sand
If more than half is sand, the soil is sandy
If more than half is clay, the soil is clay.
Excavating the foundation trenches --- The inner sides of the trenches must be as vertical as possible. --- Dig out the foundation trenches using the chalk marks as guidelines.
The trenches must be clean and free from any organic components
The bottom must be leveled clean and without loose soil
If it is difficult to level the bottom of the trench, you can pour a poor concrete mix (1:10) so that the bottom of the trench is level.
Page 23 Before pouring the footing Standing column reinforcing bars Placing installations Assemble the reinforcing bars for each column. Then stand the assembly in place where the column will be. On page 26 you will find details. Have the utilities and plumbing for your house ready before laying the foundations. The pipes must never pass through any reinforced concrete element such as columns, beams or roof joists. Pipes crossing continuous footings must have a diameter less than 16 cm (6 in.) To assure that the steel assemblies are always vertical, fasten them with #8 wire. Plinth Assembly stirrups The steel bars of the columns rest on the bottom of the foundation and must be bent with an anchorage length of 25 cm Footing If it is necessary for pipes to pass over the footing, try to make sure that all of them cross at the plinth. Wetting the trenches Wet the trenches before pouring concrete for the foundation Always leave some tolerance in the footing so that pipes are not trapped. Tolerance Recommendations You can leave holes in the foundation fo rthe pipes, using larger-diameter pipes. You can leave holes in the foundation for the pipes, using larger-diameter pipes. Before pouring concrete for the foundation, fill the pipes with sand and seal them temporarily. Never leave sand bags in the foundation to provide holes for crossing pipes