Do-it-yourself dry warm water floor in a wooden house

Dry floor heat­ing in a wood­en house or a screed is a ques­tion that many peo­ple ask them­selves when they plan to car­ry out repairs and equip a heat­ing sys­tem. The sec­ond option has been more pop­u­lar for a long time and has high­er ther­mal con­duc­tiv­i­ty, which means that rooms with it are warmer and more com­fort­able.


Dry warm floor has less weight, which does not cre­ate sig­nif­i­cant pres­sure on the floor beams. This is the main rea­son why wood­en hous­es pre­fer this tech­nol­o­gy over con­crete screed. It can be used both in build­ings under con­struc­tion and exist­ing ones, and there is no need to wait for a long time until the solu­tion is com­plete­ly dry. When using wet tech­nol­o­gy, you have to wait about 25–28 days before start­ing fin­ish­ing work. Instal­la­tion of a dry floor is car­ried out much faster, there is less debris from it, and soon after the start of work, the room can be used.

The dis­ad­van­tages of the design include the fact that a num­ber of ele­ments in a dry screed are afraid of mois­ture, so addi­tion­al water­proof­ing must be used dur­ing instal­la­tion.

Dry warm floor in a wooden house
Dry warm floor in a wood­en house

When is dry underfloor heating used?

Dry under­floor heat­ing is usu­al­ly applied under a num­ber of con­di­tions in which it is the most opti­mal solu­tion. These include:

  • Low room height. Also, rais­ing the floor lev­el may be unac­cept­able in accor­dance with cer­tain archi­tec­tur­al or design deci­sions. The min­i­mum thick­ness of a dry floor can start from 35 mm, while for a con­ven­tion­al screed it is at least 80 mm.
  • Weak cov­ers. The weight of a dry sys­tem does not exceed 30 kg per 1 m², while for a con­crete screed this fig­ure can reach 300 kg. In frame and pan­el hous­es, such a load is unac­cept­able.

There are sev­er­al tech­nolo­gies for arrang­ing a dry warm floor in a wood­en house, which depend on what kind of floor­ing will be used in the future, and what screed mate­ri­als are rel­e­vant in a par­tic­u­lar case.

Impor­tant! What­ev­er tech­nol­o­gy you choose, you should always remem­ber about the pre­lim­i­nary prepa­ra­tion of the sur­face. It must be thor­ough­ly cleaned of any debris and lev­eled to an accept­able drop rate (2 mm per lin­ear meter).

Dry warm floor in a wooden house under the laminate

The tech­nol­o­gy of installing a dry floor heat­ing in a wood­en house under a lam­i­nate has its own char­ac­ter­is­tics. First of all, it is nec­es­sary to choose the right coat­ing that is best suit­ed for these pur­pos­es. Here you need to con­sid­er the fol­low­ing:

  1. Lam­i­nate itself has a fair­ly low ther­mal con­duc­tiv­i­ty and is a good heat insu­la­tor. For under­floor heat­ing to work as effi­cient­ly as pos­si­ble, give pref­er­ence to boards of small thick­ness.
  2. Lam­i­nate, belong­ing to a high class, is resis­tant to tem­per­a­ture and humid­i­ty, is less prone to dry­ing out and defor­ma­tion.
  3. When choos­ing a sub­strate for a lam­i­nate, it is bet­ter to give pref­er­ence to mate­ri­als that are specif­i­cal­ly designed for under­floor heat­ing sys­tems.
Dry water heated floor under the laminate
Dry water heat­ed floor under the lam­i­nate

The technology of laying a dry water floor under a laminate

A water heat­ed floor in a wood­en house with a dry screed, laid under a lam­i­nate, is not the best solu­tion in terms of heat trans­fer. At the same time, this method is the fastest for warm­ing the sur­face, and even if it is not enough to heat the sur­round­ing space, you will pro­vide your­self with pleas­ant walk­ing on heat­ed boards.

Instal­la­tion is car­ried out as fol­lows:

  1. A water­proof­ing lay­er is laid on the sur­face.
  2. Bulk mate­r­i­al is back­filled, which is ordi­nary sand, expand­ed clay screen­ings or a pro­fes­sion­al dry mix.
  3. Bea­con pro­files are exposed, with the help of which the future floor is lev­eled.
  4. One of the most impor­tant points is the lay­ing of pro­filed alu­minum plates that per­form a heat-dis­trib­ut­ing func­tion.
  5. Lay­ing pipes in the recess­es of the plates.

Impor­tant! After this step, check the floor sur­face again and make sure there are no pits or bumps. On the poured sur­face, you can move around with the help of a “bridge” — a sheet of ply­wood shift­ed to the right place.

  1. A porous tape is mount­ed around the entire perime­ter of the room, damp­ing noise from shock loads.
  2. The floor is cov­ered with sheet mate­ri­als, which can be OSB, dry­wall or ply­wood. Lay­ers must be made with over­lap­ping seams, fas­ten­ing them with self-tap­ping screws at a dis­tance of 15 cm for OSB and ply­wood, and 5 cm for dry­wall.
  3. A sub­strate of min­i­mum thick­ness with the max­i­mum avail­able ther­mal con­duc­tiv­i­ty is mount­ed.
  4. Lam­i­nate is being installed.

Tip: Lam­i­nate is afraid of rapid tem­per­a­ture changes, so if you want it to last you as long as pos­si­ble, do not heat the floor more than 5 degrees a day. Also, do not allow its sur­face tem­per­a­ture to exceed 28 C.

Dry water heated floor according to Finnish technology

Dry water heat­ed floor accord­ing to Finnish tech­nol­o­gy is a good solu­tion for instal­la­tion on logs. An ordi­nary con­crete screed per­forms two main func­tions: it fix­es the sys­tem and trans­fers heat upwards. Due to its heavy weight, it is not always pos­si­ble to use it in wood­en hous­es, which is why a fair­ly effec­tive alter­na­tive was invent­ed. In the Finnish ver­sion, its role is played by gyp­sum-fiber sheets laid in sev­er­al lay­ers between pipe loops and being the basis. The voids between all com­po­nents of the struc­ture are filled with tile adhe­sive. Fin­ish­ing mate­r­i­al is attached from above in the usu­al way.

GVL sheets
GVL sheets

A warm water floor on wood­en logs with the help of GVL has a low weight and exerts an allow­able load on the floors. Com­pared to con­ven­tion­al dry­wall, this mate­r­i­al is more resis­tant to bend­ing and defor­ma­tion, while being char­ac­ter­ized by increased ther­mal con­duc­tiv­i­ty. The desired height of the screed can be eas­i­ly achieved by sim­ply bond­ing the slabs togeth­er with tile adhe­sive. Gyp­sum fiber sheets also have such advan­tages as:

  • Afford­able cost.
  • Ease of pro­cess­ing.
  • Envi­ron­men­tal friend­li­ness.
  • Fire safe­ty.

Anoth­er advan­tage of such a floor is that in the event of a leak, it is much eas­i­er to repair than with a con­crete screed.

Tip: For dry under­floor heat­ing screed today, not only GVL is used, but also sheets of chip­board, OSB or ply­wood. On sale you can find ready-made kits, the mate­r­i­al in which already has the shape nec­es­sary for con­ve­nient instal­la­tion.

How is the installation of a dry screed according to Finnish technology

Instal­la­tion of a water floor accord­ing to Finnish tech­nol­o­gy involves a stan­dard lay­ing algo­rithm, regard­less of the type of slabs used. In order for the heat to be prop­er­ly dis­trib­uted and rise up, great atten­tion must be paid to insu­lat­ing mate­ri­als: a vapor bar­ri­er is laid between the lags, a heater is placed on it, and then anoth­er lay­er of vapor bar­ri­er that will pro­tect the tree from con­den­sa­tion.

Dry warm floor with GVL sheets
Dry warm floor with GVL sheets

If you do not use a ready-made dry screed kit, the tech­nol­o­gy for fur­ther instal­la­tion will be as fol­lows. With the help of self-tap­ping screws, GVL sheets are attached to the lags, on the sur­face of which a fur­ther route for the pas­sage of water pipes is applied. After that, they begin to cut the mate­r­i­al into strips and attach it to the base.

Tip: The dis­tance between the strips of gyp­sum fiber boards should be slight­ly larg­er than the diam­e­ter of the pipes. So it will be more con­ve­nient for you to car­ry out lay­ing, and in the future, in any case, all voids will need to be filled with tile adhe­sive.

Floor in the bathroom of a wooden house with a dry screed of a warm floor

In con­nec­tion with the process­es tak­ing place in the bath­room, spe­cial require­ments are imposed on the struc­tures and fin­ish­ing mate­ri­als used in this room. The great­est atten­tion should be paid to the floor, as it gets the most water. If the room is locat­ed on the sec­ond floor, it is impor­tant to take care not only that the coat­ing lasts as long as pos­si­ble, but also to be sure that the low­er rooms are pro­tect­ed from leaks.

A bath­room floor in a wood­en house with a dry under­floor heat­ing screed will cost a lit­tle more than a sim­i­lar option in oth­er rooms, since in this case more mate­ri­als are used. The tech­nol­o­gy that involves the use of spe­cial­ized mix­tures that can be bought at any hard­ware store is con­sid­ered the most opti­mal. First, the sur­face with a lay­er of vapor bar­ri­er laid on it is cov­ered with expand­ed clay mate­r­i­al, on which a dry screed is dis­trib­uted. Sheets of mois­ture-resis­tant dry­wall are mount­ed on top, which will pro­tect the sys­tem from mois­ture pen­e­tra­tion from the out­side. As in oth­er cas­es, the perime­ter is glued with a spe­cial poly­eth­yl­ene tape that damp­ens impact noise.

Dry screed in the bathroom from a specialized mixture
Dry screed in the bath­room from a spe­cial­ized mix­ture

This tech­nol­o­gy of lay­ing a dry warm water floor in the bath­room is the least labor-inten­sive and there is prac­ti­cal­ly no dirt dur­ing oper­a­tion. The main dis­ad­van­tage in this case is the inabil­i­ty to with­stand high loads.

One of the most impor­tant steps when lay­ing a dry screed in the bath­room is the prepa­ra­tion of a water­proof­ing lay­er. Expe­ri­enced spe­cial­ists sug­gest using bitu­mi­nous mas­tic or roll mate­ri­als. With their help, you can pro­tect not only the floor itself, but also the base of the walls, which are cap­tured to a height of up to 20 cm.

Advice: instead of the usu­al mois­ture-resis­tant gyp­sum, you can use Knauf GVL-plates, which are strong enough and can with­stand weight up to 1000 kg per square meter. This option will be opti­mal for rooms where it is planned to use heavy fin­ish­ing mate­ri­als for the floor and large-sized fur­ni­ture.

Water heated floor: dry installation on foam plastic on a wooden floor

Poly­foam has excel­lent ther­mal insu­la­tion prop­er­ties, and there­fore it is wide­ly used in con­struc­tion for insu­la­tion of struc­tures. Also, its advan­tage is its low weight, which does not affect non-over­lap­ping. Due to these fea­tures, dry instal­la­tion of a water-heat­ed floor on poly­styrene foam on wood­en floors is often car­ried out. This mate­r­i­al has a num­ber of oth­er advan­tages, name­ly:

  • Char­ac­ter­ized by zero water absorp­tion.
  • Does not pass mois­ture and steam.
  • It has excel­lent sound-absorb­ing prop­er­ties.
  • With­stands heavy loads.
  • Has an afford­able price.
Underfloor heating on foam
Under­floor heat­ing on foam

With the help of foam, you can fin­ish the sur­face for a water-heat­ed floor, even with­out spe­cial build­ing skills. This mate­r­i­al is eas­i­ly cut and mount­ed on the sur­face of any con­fig­u­ra­tion. Along with a low price, it is char­ac­ter­ized by a rather long ser­vice life, for which it is appre­ci­at­ed by con­sumers. The only sig­nif­i­cant draw­back of poly­styrene is its flam­ma­bil­i­ty: it ignites at tem­per­a­tures above 180 degrees, and releas­es tox­ic sub­stances into the envi­ron­ment, which in a nor­mal state do not harm in any way.

Tip: If you plan to install a warm floor with foam insu­la­tion on the ground floor of the build­ing, it is bet­ter to give pref­er­ence to slabs 8–10 cm thick. On oth­er floors, 4–5 cm will be enough.

Polystyrene underfloor heating system
Poly­styrene under­floor heat­ing sys­tem

The tech­nol­o­gy for installing a dry warm floor on foam plas­tic on a wood­en floor is as fol­lows. Ther­mal insu­la­tion boards are the basis that is laid on the floor. Fur­ther, heat-dis­trib­ut­ing met­al plates made of gal­va­nized steel or alu­minum are placed on them. They not only pro­vide uni­form heat­ing of the floor sur­face, but also ensure the fix­ing of the sys­tem pipes insert­ed into their grooves. Addi­tion­al rigid­i­ty is giv­en by two sheets of GVL, which are placed on top in a checker­board pat­tern. The rec­om­mend­ed thick­ness of such a coat­ing is 1 cm.

When arrang­ing a warm water floor under a screed on a wood­en base, you can use both ordi­nary foam plas­tic and more mod­ern mate­ri­als — poly­styrene or foam plas­tic. They have a high­er cost, but at the same time they sig­nif­i­cant­ly ben­e­fit in terms of their char­ac­ter­is­tics. Plates have dif­fer­ent mark­ings, which is an indi­ca­tor of their den­si­ty.

Tip: More com­fort­able than reg­u­lar smooth foam are poly­styrene mats with ledges (boss­es). Met­al plates with pipes are laid out in the space between them, where they are secure­ly fixed and do not move dur­ing sub­se­quent oper­a­tion. The side sur­faces of such plates have spe­cial assem­bly locks that allow them to be con­nect­ed into a con­tin­u­ous web.

Con­clu­sion. Dry screed is much faster than con­crete screed, requires much less labor and is light in weight. All this makes it ide­al for use in wood­en hous­es, where high loads on floors are unac­cept­able. At the same time, it is more sus­cep­ti­ble to mois­ture, there­fore, it requires a more care­ful atti­tude to the con­struc­tion of the water­proof­ing lay­er.


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