What is the cheapest way to add space: build an attic or basement? [Comparison, analysis, results, conclusions]

  • Dec 11, 2020

Good afternoon, dear guests and subscribers of my channel!

In this article, I will not touch on the features of the site in terms of the groundwater level, but I will consider the ideal option, where you can make both the basement and the attic. And the task boils down to the following:

There is a ready-made layout for a one-story house, i.e. the owner likes the configuration of the premises and does not want to change it. But! A person, before starting construction, wants to add another area at the lowest cost, without changing the plan of the house. Which will be cheaper to do: basement or attic?
Understanding... at the end I will give a summary table.

1. Foundation

For the construction of the basement, you need to dig a pit, which cannot be said about the attic. For comparison, the basement room of the house 10 * 10 is about 300 cubic meters in volume, and the size of the pit is as at least 1 m more in each direction from the axes of the house, so the volume of excavation will be ~ 400-450 cbm

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Source: https://vovdi.ru/skolko-stoit-vyryt-kotlovan-pod-fundament-doma-na-dache/

The cost of the excavator will be about 30,000 - 50,000 thousand rubles. If the soil needs to be transported to the landfill, this is another 250-350 rubles. from each cubic meter. Already more than a hundred thousand for export runs, so it is easier to stretch the soil over the site. These works remain at the discretion of the owner.

2. Floors

The walls of the basement are the walls of the foundation, while the floor can be made using flooring technology on the ground or as a monolithic reinforced concrete slab. Therefore, when organizing a basement floor, there are costs for the construction of the floor, plus welded waterproofing for the entire floor area. All this costs will be from 90,000 to 120,000 rubles. no work.

You can object and say that in the attic you will also have to throw plates on the floor... I will not deny, but the basement floor also needs to be covered and a floor for the first floor must be constructed, which will be much more expensive than conventional ground floors in the absence of a basement.

AUTHOR'S PHOTO - floor on the ground

Overlapping the basement floor, the costs come out almost the same, and are comparable to the organization of the overlap between the first and attic floors, depending on the type of construction. The cost for a 10x10 house is about 90-150 thousand rubles, but if this is a monolithic reinforced concrete floor, then add another 30-40% to this price (formwork rental + concrete pump + work).

3. Walls

For most regions of Russia, in order to organize the basement floor, the walls of the foundation must be built almost twice as deep as the construction of the foundation without a basement suggests.

Also, the basement floor in central Russia is characterized by the insulation of all foundation walls outside the building with a hermetically made waterproofing. Again, for a 10x10 house, the area of ​​the foundation walls in contact with the ground is ~ 120 square meters, which means that the costs are at 100 mm. a layer of insulation will be equal to the cost of 12 cubic meters of expanded polystyrene, which is 57,000 rubles. + surfacing waterproofing about 10-15,000 thousand rubles If you hire craftsmen for these purposes, then at least 30,000 rubles are added.

The cost of the walls of the attic floor is relatively low, since the gables will be in the usual cold attic.

AUTHOR'S PHOTO - attic

But, of course, it is important here to take into account the needs of the owner and his requests for the height of the attic. In order not to bang your head on the roof, the minimum height should be at least 1.7 m. Accordingly, the walls on the four sides of the house will rise by an additional 1.7 m.

For a 10 * 10 house, when all the walls are raised by 1.7 m, the total square of the walls will increase by 70 sq. M. - and this is already essential. But, do not forget that when organizing the basement floor, we also need to deepen to about the same distance.

As for the stairs, it will be in one and in the other case, so I am not considering it.

4. Roof

The mansard roof takes the lion's share of the savings. Here it is necessary to ensure the complete tightness of the room against blowing by the wind and complete vapor barrier.

Therefore, you will have to spend money on hydro-wind protection, vapor barrier and insulation, at least 20 see, and this is an increase in the cross-section of the roof rafter legs, and, accordingly, an increase in the volume of the purchased lumber.

AUTHOR'S PHOTO - insulation

Returning to our house 10x10, the area of ​​the roof slopes with a slope of 35 degrees and overhangs of half a meter will be approximately equal to 170 sq.m. Thus, with a thickness of insulation of 200 mm. you will need (170 * 0.2) 34 cubic meters. insulation or ~ 70,000 rubles. + hydro and vapor barrier ~ 15,000. Thus, the additional costs will amount to 80,000 rubles. no work.

We add the cost of work (40,000 rubles) and the difference in lumber (12,000 rubles). Total: 132,000 rubles.

5. Communications

If there is a bathroom in the basement, then the sewage system needs to be buried accordingly, which means that it is necessary make a septic tank deeper, and the lowest point of drainage will be at a depth of at least 2.5 meters from the level land. There is an extra height of the cesspool.

The rest of the communications remain intact: both there and there need water and heating - the costs are identical.

6. Expenses for everything that depends on the height

The attic floor adds at least 1.5 meters of height to the house, this can be judged from the illustration (I put down the elevation marks):

Therefore, additional costs will go to the construction of a chimney and ventilation - an extra 1.5 meters in height. In addition, all pipes of the drainage system are lengthened by 1.5 m, but this is already a trifle.

AUTHOR'S PHOTO - gutter

7. Window

We will not leave the attic floor without windows, otherwise the house will look terrible and inside will not be very comfortable. These are either full-fledged windows, or at least two roof windows. It's still a cost!

When organizing a basement, you can leave small windows 40-50 cm high, which come out at a much cheaper cost.

8. Finishing

We do not consider finishing, since it all depends on the preferences of the owner. The square is the same, in our case we will equate these costs.

Outcome

Comparison chart for our example 10x10 house:

Conclusion (From the author)

Despite the fact that these are both completely different designs, the costs remain approximately equal at completely different cost items. As you can see, increasing the area of ​​the house, the price per square meter remains the same.

Of course, the cost of each item cannot be accurately calculated, there are a lot of variables that depend on the formed values, preferences, position and views of the owner of the house directly. But, even if there are errors in the numbers, we got a real picture of the costs for each item.

The summary table presents to the analysis those points that can be worked out in the process of designing a house and this provides a good opportunity to optimally build a sequence of tasks and their solutions in order to reduce the cost of construction processes NOT IN DAMAGE QUALITY.

Hope you enjoyed it!

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