How Much Does Soil Boring Cost in 2026?
SPN's soil boring price for 2026 starts at roughly THB 20,000–40,000 for a 2-storey detached house (2–3 boreholes) and rises with the number and depth of boreholes as buildings get larger. There is no "single price" for soil boring; it depends on 5 main variables: number of boreholes, depth, project location, site conditions and the type of lab testing. The table below shows SPN's starting prices by building type, for setting a rough budget before requesting an actual quotation.
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| Project type | No. of boreholes | Depth | Starting price (excl. travel) |
|---|---|---|---|
| 2-storey detached house | 2-3 boreholes | 20-30 m | THB 20,000-40,000 |
| Townhouse/townhome | 2-3 boreholes | 20-30 m | THB 20,000-50,000 |
| 3-4 storey shophouse | 3-4 boreholes | 25-30 m | THB 30,000-70,000 |
| Condominium/apartment | 4-8 boreholes | 40-60 m | THB 100,000-500,000 |
| Factory, 1,000 m² | 4-6 boreholes | 30-40 m | THB 40,000-150,000 |
| Bridge/road (per kilometer) | 10+ boreholes | 30-50 m | THB 300,000-1,000,000+ |
* The prices above are approximate starting prices, including field work, basic lab tests and a report certified by a licensed engineer. Travel and equipment mobilization are not included, nor is VAT.
* Depths refer to the Engineering Institute of Thailand (EIT) guideline of 2008 and are adjusted to the actual soil profile at each site — see the termination criteria in the depth standards section below.
What Determines Soil Boring Cost? 5 Main Variables
Soil boring cost variables are what make quotations for plots of similar size differ so much. They fall into 2 groups: fixed costs per trip (rig mobilization, travel, setup) and costs that vary with the quantity of work (number of boreholes, depth and number of samples sent to the lab). The diagram below shows where each variable sits in an actual job.
1. Number of Boreholes (Boring Points)
The more boreholes drilled at the same site, the lower the average price per borehole, because setup, mobilization and travel are fixed costs that can be spread across many boreholes. A single borehole therefore has the highest price per hole, since it carries the full fixed cost.
Overall comparison of average price per borehole (the more you drill, the less each borehole costs):
- 1 borehole: highest price per hole — used as the baseline (100%)
- 2–4 boreholes: about 10–20% less per hole than a single borehole
- 5 or more boreholes: about 15–30% less per hole — best value per hole
The percentages above are approximate and depend on depth, distance and actual site conditions — see the total starting prices by building type in the table above, or request a free quotation within 24 hours for a price that matches your site.
2. Depth (Boring Depth)
Deeper boreholes cost more because they take longer and may need special equipment:
- 15-30 meters: standard price
- 30-50 meters: +30-60%
- Over 50 meters: price by agreement; specialized equipment required
3. Project Location
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| Area | Travel/mobilization | Remarks |
|---|---|---|
| Bangkok and vicinity | Charged by distance (lowest starting rate) | Easy access, short distance |
| Central Thailand | +THB 2,000-8,000 | Distance up to 200 km |
| Eastern Thailand | +THB 2,000-12,000 | Rayong, Chon Buri, Chanthaburi |
| Northern/Northeastern Thailand | +THB 10,000-25,000 | Depends on number of overnight stays |
| Southern Thailand | +THB 15,000-30,000 | Travel and accommodation |
| Remote areas/islands | Price by agreement | Site assessment required |
4. Site Conditions and Job Difficulty
Normal work on flat ground is charged at the standard price, but for:
- Drilling in a river/the sea — requires a pontoon and specialized equipment, price +100-300%
- Drilling under a bridge/inside a building — requires a compact rig, price +30-50%
- Drilling into rock (Rock Coring) — price +50-150% depending on rock hardness
- Sloping ground/hillsides — additional access must be built, price +20-40%
5. Type of Lab Testing
The 5 basic lab tests are already included in the standard price, while advanced tests are charged extra per sample (to learn what each test measures and which jobs it suits, see What Laboratory Soil Tests Are There?). The basic tests are:
- Natural Water Content (ASTM D2216)
- Unit Weight (ASTM D7263)
- Atterberg Limits (ASTM D4318)
- Unconfined Compression (ASTM D2166)
- Sieve Analysis (ASTM D6913)
Advanced tests add to the price:
- Consolidation Test (ASTM D2435): +THB 2,000-5,000/sample
- Triaxial Test (ASTM D4767): +THB 9,000-18,000/sample
- Direct Shear (ASTM D3080): +THB 3,000-5,000/sample
- CBR Test (ASTM D1883): +THB 3,500-6,000/sample
How Deep Should Boreholes Be, and How Does Depth Affect Price?
Borehole depth is not chosen at random. It follows geotechnical engineering principles in the guidelines of the Engineering Institute of Thailand (EIT), together with SPT results per ASTM D1586 obtained while drilling. As a general rule the depth should be about 2–2.5 times the short side width of the building, because at that level the stress added by the building load has dropped to a small fraction of that beneath the foundation. The real governing factor, however, is that drilling must reach the bearing stratum (dense sand/hard soil) that can actually carry the building.
Roughly, houses and buildings of up to 5 storeys are usually drilled to about 25–30 m, while high-rise buildings may go to 40–60 m or more. Bangkok and its vicinity, with thick soft soil layers, usually require deeper boreholes than the provinces — the full depth table by building type and area (Bangkok vs. provinces), with the EIT 2008 reference criteria, is in the article How Many Boreholes and How Deep?, our main reference page on borehole numbers and depth. In price terms, depth is the strongest variable after the number of boreholes, because drilling is charged by depth and working time; boreholes of 30–50 meters therefore add about 30–60%, as in the depth category above.
The depths above are approximate. In practice, drilling continues until a dense sand/hard soil layer with an SPT N-value greater than 35 is found continuously for at least 3 meters (heavier buildings use higher criteria, e.g. N greater than 40–45 and a thicker layer). If rock is found at shallow depth, drilling must continue at least 3–5 meters into it to confirm it is bedrock and not a boulder (per EIT guidelines). To understand how N-values are read and interpreted, see How to Interpret SPT N-Values
Some areas of Bangkok and some provinces have soft soil layers that are much deeper and thicker than normal (e.g. some areas along old river courses or along filled-in former canals), which requires drilling deeper than the standard table above. This directly affects the price under the "depth" category discussed earlier (the 30–50 meter range adds about 30–60% under the depth category). If your land is in one of these areas, tell the engineer when requesting the quotation so the price can be estimated accurately — for the full details of risky soil zones in Bangkok and by province, see Bangkok Soft Clay vs. the Provinces — Why Foundations Are Designed Differently
References: Engineering Institute of Thailand (EIT) · ASTM D1586 (Standard Penetration Test) · For all standards used in soil investigation, see ASTM Standards in Soil Investigation
Is Soil Boring in the Provinces More Expensive Than in Bangkok?
A popular question from landowners outside Bangkok is "how different is the price from Bangkok?" The answer is that it can be either cheaper or more expensive, because two forces pull in opposite directions. On the cheaper side: in most provinces the hard soil layer is shallower than in Bangkok, where boreholes must pass through thick soft clay. In many areas drilling only needs to reach the level that meets the termination criteria (see the depth table and termination criteria in the previous section), so the drilling cost, usually the largest part of the job, is lower. On the more expensive side is moving the rig and crew (Mobilization), which varies with distance and the number of overnight stays, per the travel cost table in the project location section above.
Besides distance, the factors that make two provincial jobs cost differently include:
- Site access — land fronting a main road and an orchard where vehicles must push in several hundred meters have different costs; in some cases a special compact rig or a temporary access road is needed
- Water source for drilling — wash boring requires water; if there is none on site, it must be supplied
- Number of boreholes per mobilization — moving the rig a long way to drill a single borehole means a high mobilization cost per hole; combining several boreholes or locations in one trip spreads the cost considerably
- Soil type — gravel, rock or very hard soil slows drilling and raises the cost per meter, and some provinces have soft layers beneath hard layers that cannot be seen from the surface, which may require deeper drilling or more boreholes than expected
The way to get the best value from a provincial job is to combine the work into a single trip — if you have several plots, or neighbors/nearby projects also need boring, scheduling them together shares the mobilization cost. You should also send complete site information from the start: plot coordinates, photos of the access, and the distance from the road to the boring points. The provider can then price accurately without adding a risk allowance. Do not compare only the total figures without checking what each quotation includes.
SPN Soil Engineering provides soil investigation in all 77 provinces, including offshore work, and our team is familiar with soil conditions in many regions. Prices for houses start at roughly THB 20,000–40,000, while provincial jobs depend on location and scope of work. Send us the coordinates and project details and get a free quotation within 24 hours. Call 064-746-9601 or LINE @spnth
How Can You Save on Soil Boring Without Reducing Data Quality?
The right way to save is to "cut what is unnecessary", not to "cut data quality", because inadequate data costs more in the long run.
1. Combine Boring Work into One Project
If you have bought several adjacent plots, plan to do all the boring in one go. Setup and travel are paid once, so the fixed cost is divided by more boreholes (see the diagram below) — and if you are still deciding whether to buy, 1–2 screening boreholes before transfer help estimate the foundation budget in advance; see Should You Do Soil Boring Before Buying Vacant Land?
2. Consult an Engineer Before Setting the Number of Boreholes
The number and location of boreholes should be set by an engineer according to the building size and project requirements — no more or fewer than necessary. For large areas or light structures, the engineer may add low-cost probing such as KPT or DCP between boreholes to check the uniformity of shallow soil layers — compare the methods at DCP vs KPT vs SPT
3. Avoid the Rainy Season If Possible
Boring in the rainy season (May–October) may be delayed and incur extra costs for water protection. Try to plan drilling for November–April and allow enough time in the schedule — see the timeline from booking to report at How Long Does Soil Boring Take?
4. Get Quotations from 2-3 Companies
But do not just pick the cheapest. Check the engineer's license (COE), lab equipment calibration certificates and project portfolio. Unusually low prices often come with substandard quality.
What Should a Soil Boring Quotation Include?
Before comparing prices, always compare the "scope of work" first — a proper quotation should clearly list the following items (for detailed criteria for choosing a company, see How to Choose a Soil Boring Company: 7 Checks Before Hiring, and for what the report must contain for a building permit application, see Legal Soil Investigation Report Checklist):
- ✅ Drilling cost by number of boreholes and depth
- ✅ Basic lab tests, 5 or more items
- ✅ Travel/equipment mobilization and crew accommodation (stated separately by distance)
- ✅ Boring Log + Soil Profile report
- ✅ Analysis and foundation design recommendations
- ✅ Licensed engineer's signature on every report
Some companies quote a low price and then add charges later, such as additional analysis, pile capacity calculation, or report delivery. Ask clearly before signing the contract.
What Percentage of Construction Cost Is Soil Boring?
Soil investigation typically costs only 0.3–1% of total construction cost. For example, for a house with a THB 3 million construction budget, soil boring of about THB 20,000–30,000 is less than 1%, yet the soil data obtained is what the engineer uses to design the foundation of the entire house.
Soil investigation usually accounts for 0.3–1% of total construction cost, whereas fixing a foundation after construction — such as adding piles beneath a building in use — is difficult and usually costs many times more than the soil boring. Investing less than 1% up front is therefore worthwhile.
Summary
Soil investigation prices in 2026 start at roughly THB 20,000–40,000 for a 2–3 storey house (2–3 boreholes, including basic lab tests and an engineer-certified report, excluding travel and equipment mobilization) and run to hundreds of thousands of baht for large projects. Five main variables set the price: number of boreholes, depth, project location, site conditions and type of lab testing.
Investing in quality soil boring saves construction and repair costs in the long run. See the full scope of work and procedure on our soil investigation and testing service page, and if your project also needs pile testing, read on at Pile Testing Prices 2026. Contact SPN Soil Engineering for a free, accurate quotation for your project within 24 hours.