Soap-treated wooden floors: care and cost

Øens HåndværkerCentralPublished August 12, 2026 · 11 min. read

A soap-treated floor is a wooden floor where the surface is saturated with wood soap instead of lacquer or oil. The soap leaves fatty acids in and on the wood, preventing dirt from easily penetrating the fibres. Gulvfakta from the Danish Flooring Association under DI (accessed August 2026) recommends at least 2 soap treatments before the floor is put into use.

• 175 kr/m2Including VAT and a standard finish, from 36 m2
• 24 hoursResponse with fixed price
• Workmanship guaranteeOn all work performed

What is a soap-treated floor?

A soap-treated floor is an untreated or lye-treated wooden floor that has been washed several times with wood soap until the surface is saturated. There is no film of lacquer or hardening oil. Gulvfakta from the Danish Flooring Association under DI describes the desired outcome as a saturated, uniform surface without overlaps, with a white-grey silky matt sheen, and the surface must not be rough.

This is the treatment that most resembles untreated wood. The fatty acids in the soap fill the pores of the wood, so the floor remains light instead of yellowing. This is why you often see this treatment on wide pine and spruce planks in older townhouses in Frederiksbjerg and Aarhus C, where the floor needs to look old without being dark. Wear marks appear in the wood itself, not in a surface film, and they are gradually smoothed out each time the floor is washed with soap.

How do you soap-treat a newly sanded wooden floor?

Soap treatment of a wooden floor takes place in several stages on a finely sanded, dust-free floor. Gulvfakta from the Danish Flooring Association under DI recommends at least 2 treatments before the floor is put into use. Junckers specifies a dosage of 250 ml of Natural Soap to 5 litres of warm water.

1. Sand the floor finely and vacuum thoroughly. The soap highlights everything the sanding has left behind, so scratches and overlaps will be clearly visible afterwards.
2. Consider lye first. Gulvfakta states that lye treatment is not a surface treatment, but a preparation for a surface treatment, e.g., with soap, wax or oil. Junckers suggests that you consider lye-treating a new or newly sanded floor with wood lye before it is soap-treated. Read more about lye as a pre-treatment for wooden floors.
3. Mix the soapy water according to the manufacturer's instructions and distribute it in an even layer with a mop or floor cloth.
4. Wipe dry with a well-wrung cloth in the direction of the wood grain. The floor must not be soaked. Junckers emphasises that a wooden floor cannot tolerate soaking, and that spilled water must be wiped up immediately to avoid moisture damage.
5. Allow the floor to dry completely, and repeat. At least twice. If the surface still appears unsaturated on thirsty softwood, an extra round may be necessary before furniture and traffic are introduced.

On hard wood species, you must use a minimum of water during soap treatment, Gulvfakta emphasizes. The harder the wood, the less it absorbs, and excess water causes streaks instead of saturation.

Oil or soap - what should you choose?

Choose soap if you want the lightest, most raw look and are happy to wash the floor with soapy water every time. Choose oil if you want more resistance to grease and water. Junckers highlights that oiled surfaces can be more easily spot-treated in heavily used areas, while a lacquered surface requires light intermediate sanding of the entire surface before it can be re-lacquered.

How long passes between each full sanding depends on wear. Junckers states as a rule of thumb that many floors are sanded every 10-20 years. If the choice is between film and penetrating treatment, the comparison of lacquering and oiling of wooden floors is a good place to start. If you already have an oiled floor, you can follow the routine in the guide to maintenance of oiled wooden floors.

Which wooden floors are suitable for soap?

Soap is best suited for soft softwood floors made of pine and spruce, where the light look is the whole point. Træinformation's TRÆfakta 09 "Lye treatment" specifically describes methods for lye treatment of softwood floors, primarily based on the combination of lye and soap treatment. On hard wood species such as oak and ash, soap can be used, but with a minimum of water.

A solid plank floor is the obvious candidate because it can be sanded down to bare wood multiple times and therefore can withstand the treatment again and again. Junckers' rule of thumb for solid floors is about 5 sandings for 14 mm thickness, 6 for 15 mm, and 8-10 for 20.5-22 mm. Engineered parquet has a thinner wear layer and tolerates fewer sandings, so soap is less often the right choice here. If you are unsure how much wood your floor has left, the guide on how many times a wooden floor can be sanded provides a concrete answer, and for wide planks, sanding plank floors is more detailed.

Kitchens and hallways are the weakest points. Soap-treated wood is sensitive to grease and standing water, which is why many choose a different treatment specifically in these rooms.

How often should a soap-treated floor be washed?

A soap-treated floor must be washed with soapy water far more often than a lacquered one. Junckers clearly describes it: re-treatment and cleaning are the same; the floor simply needs to be washed with soapy water. In return, there is no separate re-treatment, as there is when an oiled floor needs care oil.

Calculation example: soap consumption in one year. Junckers' dosage for treatment is 250 ml of Natural Soap to 5 litres of warm water. If one mixture is enough for the floor, and you wash once a week, it amounts to 52 x 250 ml = 13 litres of natural soap per year. If you wash every other week, you are down to about 6.5 litres. How many mixtures you actually use depends on the floor area, so use this figure as a calculation example when weighing soap against oil.

The rule of thumb is that the floor needs soap again when the surface starts to look dry, dull, or streaky. Water alone washes the soap out of the wood, and a floor that is only washed with clean water will become grey and rough. The general routine is in the guide to washing and cleaning wooden floors.

What does sanding and soap treatment cost?

The standard rate for floor sanding with a standard finish is 175 kr per m2 including VAT from 36 m2. Smaller areas have fixed prices. The floor condition, access and any repairs are assessed before we confirm the quotation; standard finish choices share the same base rate.

The figures are calculated directly from the m² price and are not an offer. Please also note that a soap-treated floor has an ongoing cost afterwards in the form of soap and labour hours, while a lacquered floor only incurs costs again when it needs to be sanded again - according to Junckers, often every 10-20 years. See more examples and price drivers in the guide on what floor sanding costs.

Can you soap-treat the floor yourself?

You can easily handle the soap washing yourself. It's the sanding beforehand that determines the result, and that's difficult to do flawlessly with a rented machine. Gulvfakta from the Danish Flooring Association under DI requires a saturated, uniform surface without overlaps, and overlaps from a belt sander are clearly visible when the soap is applied.

Soap is less forgiving than lacquer because there is no surface film to soften the appearance of sanding marks. Stop marks and uneven passes remain visible in the wood. A solid floor also has a limited sanding allowance: Junckers gives 8 to 10 full sandings for a 22 mm floor and around 5 for a 14 mm floor. Unnecessary resanding therefore uses some of the floor's remaining life.

We sand and treat floors nationwide from our base in Aarhus Ø, provide a fixed price before starting, respond within 24 hours, and work with a workmanship guarantee on all work. See how we approach floor sanding and floor treatment, or call us at 20 98 88 11.

How do you remove streaks from a soap-treated floor?

Light streaks in a soap-treated floor are most often caused by water or cleaning agents that have washed the soap out of the wood. The solution is usually to re-treat the affected area with soap and then the entire floor to ensure a uniform surface. Junckers emphasises that spilled water must be wiped up immediately, as wooden floors cannot tolerate soaking.

Dark stains are another matter. Grease from cooking and black marks from iron and water penetrate the wood and do not disappear with soapy water alone. Here, local or full room sanding is usually required. The guide on removing stains from wooden floors reviews which stains can be saved without sanding. If the floor has just been sanded, the routine in maintaining newly sanded wooden floors helps keep the surface saturated from the start.

Frequently Asked Questions

Frequently Asked Questions

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Øens HåndværkerCentral

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