Seal bottom plate

Seal bottom plate: plate

Materials for sealing
  • sheet-shaped sealing materials:
  • Bitumen waterproof sheeting
  • Polymer bitumen sheets
  • Plastic and rubber sheets
  • liquid sealants:
  • plastic-modified bitumen thick coating
  • Bitumen and plastic mixtures
  • mastics
  • mastic asphalt
  • Liquid plastics
  • mineral sealing mud

Seal bottom plate

For a base plate, it is important to have a perfect seal. In the case of a new building, special attention should be given to this topic during planning in order to prevent future defects.

During the construction phase of the floor slab great care is required in all the details of the waterproofing so that the house stands on a dry, solid foundation.

The old building is either an already occurring lack of tightness and an effective renovation.

Or the use of the cellar should be changed and thus increase the demands on the dryness of the soil and the walls.

With the right information, an unpleasant loss event can be prevented. General information on the construction of a floor slab can be found here.

Seal base plate at new construction

Seal bottom plate: plate

In a new building often self-adhesive sealing membranes are used.

Defects in the sealing of the floor slab are among the most frequently criticized construction defects. In order not to get into this situation, every client should acquire enough knowledge to be able to judge how the planning and implementation around the topic "sealing the floor slab" can be classified.

In case of doubt it always makes sense to invest a bit more in this area. Other investments can be made up later. Later you will not come under the base plate to retrofit something.

Inform yourself and put yourself in the position to influence the quality in advance and to be able to monitor this also with the implementation with some expertise.

Prevention is definitely better than aftercare, especially in building waterproofing.

Floor seal according to DIN 18533

Newly published in July 2017, DIN 18533 regulates the sealing of earth-contacting components in new buildings. But it also applies to the renovation of old buildings as indicative.

Criteria for determining the required protective layers and protective measures for sealing a ground-based floor slab are:

1. Water impact class

It determines the effect of water on the earth-contacting components. Accordingly, the requirement for the sealing material is formulated.

2nd crack class / crack bridging class

The expected crack widening of the substrate is classified with R1-E with 0.2 mm (minimum standard) up to R4-E with up to 5 mm. They should be able to be compensated with the specific crack bridging property of the sealing material.

3. Room usage classes

These determine the requirements for the dryness of the rooms from low (such as simple storage rooms, garages) over normal (living spaces) to high demands (such as computer systems, sensitive archives).

4. Reliability requirements

The DIN describes concretely on this point, how many layers must be applied, for example, in which classes described above or how they are applied in order to meet the requirements.

Questions, co-decision and keep an eye on

Seal bottom plate: plate

As a builder, you should ask the planner or supplier quietly how the classification was made in the three classes, whether and how possible borderline decisions were made. Not least, of course, which reliability requirements are met and how.

Other things you can ask that you should definitely have a say in. And things that you should keep in mind when implementing them or for their careful and flawless execution, the construction management should ensure:

  • What results from the subsoil report for the sealing of the base plate?
  • Which measures will avoid unnecessarily high water exposure?
  • Sensitive areas for sealing are penetrations (utility lines, etc., which pass through the bottom plate), expansion joints and wall-floor connections.

Material for repair and sealing:

Bitumen Liquid Film

Bitumen coating

Repair mortar epoxy resin


Seal base plate at the old building

In the old building, there is rarely the case that one comes again from the bottom to the bottom plate. Actually, only if there is no base plate and the cellar is first excavated deeper and then retrofitted with a bottom plate. Since this can also affect the statics during execution, this should undoubtedly only be carried out by a specialized company and in that case all the above-mentioned aspects apply to the sealing of a floor slab during new construction.

Normally it's about a wet basement and it raises the question of a subsequent sealing. Cause is in most cases in an old building a lack or deficient external sealing of the floor slab and basement walls.

There are two basic options for refurbishment

Seal bottom plate: bottom

Cracks and other damage must always be remedied before sealing.

Possibility Number 1: It is excavated around the house to the ground and re-sealed from the outside.

This is the thorough variant in terms of walls. But you can not get to the bottom of the bottom plate either.

Option 2: From the inside seal the basement. This does not eliminate the cause, but is - as far as the better usability of the basement rooms is concerned - at least an improvement.

Even the only possibility when it comes to the topic of "sealing existing bottom plate retrospectively".

How to seal the walls and bottom plate?

A coat of paint or a filling with liquid sealing materials brings relief. For this purpose, offer sealing slurries, which are easy to use for home improvement. You can find out how to apply sealing sludge correctly here.

Frequently asked questions (FAQ):

Seal bottom plate necessary? If the bottom plate is not on supports, but is a ground-contacting component, a seal is definitely useful.

Seal bottom plate without cellar? Even then you should seal the bottom plate. Above all, non-basement means that the floor slab is the component that is the only one between your living space and the ground. It should give you as much protection from rising damp and heat loss as possible.

Bottom plate seal outside? Bottom plate seal sideways? In any case. The entire panel should be completely sealed from outside and at the side edges. As well as the pedestal.

Seal the bottom - instructions? A guide how you a basement, a garage floor u. Ä. Seal with sealing slurry can be found here.

Author: Christiane Baldwin - Online Editor and Handyman

Photo Credits:
  • Cover picture: Pixabay, Lucky2013
  • Sealing membrane: Amazon, SoPro
  • Man with binoculars: Pixabay, Free Photos
  • Repair: amazon, bekateq
  • Post picture: Pixabay, anaterate

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Video Board: Air Sealing and Caulking Walls