10:49AM | 04/26/04
Member Since: 04/21/04
4 lifetime posts
What is the best product to coat poured concrete foundation for dampproofing? Where to get it? Thanks


10:15AM | 04/28/04
Member Since: 01/28/03
693 lifetime posts
There is little apart from some commercial type of epoxy coatings or an EDPM seamless galvanized rubber membrane place on the outside of a foundation that will actually 'damp-proof' a basement.

Traditional tar-based foundation coatings which will 'waterproof' a basement to a large degree actually do nothing to get gaseous ground based water from penetrating in towards the basement.


06:00PM | 04/28/04
Member Since: 11/06/02
1280 lifetime posts
Homebuild, I think you may be mixing terms here.

Traditional damp-proofing, or mositure proofing is done with asphaltic coatings rolled on, and damp-proofing is never intended to make for a perfectly waterproof wall. Damp-proofing only protects against moisture penetration when proper soil drainage systems are in place to guide water away form the wall and footing.

Waterproofing is the proper term for the EPDM and other serious coatings for application in submesed conditions. This is normally applied professionally and is a far better quality job but beond the budget for the average HO.

Excellence is its own reward!


01:56PM | 05/02/04
Member Since: 01/28/03
693 lifetime posts
While 'tar' based coatings will in fact 'waterproof' a foundation. These tar based coatings will NOT 'damp-proof' a basement because tar does not BLOCK the passage of water in gaseous form.

This is why otherwise 'dry' basements can fell 'damp', because in fact they are.

Gaseous water will pass thru the masonry foundation and the 'tar coatings' even though the 'tar' will keep out water in liquid form.

No confusion.

Tar does not 'damp proof' and never has.

Tar is quite permeable to gaseous water.


08:20PM | 05/02/04
Member Since: 11/06/02
1280 lifetime posts
No need to get your knickers in a knot Home, but I did this professionally on government contracts for several years. i'm familiar with the difference, Any wal that has been waterproofed is damp-proofed, but a damp-proofed wall is not necessarily waterproof.

a dampproofed wall will resist most moisture penetration unitil that moisture ( in any form) is under pressure, such as from a rising water table. Then it is necessary to have a foundation waterproof with a membrane.

It has absolutely nothing to do with how a basement "feels". The definitions are objective, not subjective. A damp feeeling can exist in a waterproof cellar simply from condensation out of the interior air on the cool surfaces.

Excellence is its own reward!


07:32PM | 05/03/04
Member Since: 01/28/03
693 lifetime posts
Thanks for the reply Piffin, but I can assure you there are no knickers here and far less any 'knots' in them from my 'end'.

What you have explained seems to be government "jargonese" and not necessarily 'plain talk' but I am open to be instructed in both.

It is my understanding that although foundation coating 'tar' will resist water because of its chemical and electrical makeup (IE oil repels liquid water) the same characteristics do not occur when gaseous water interfaces with "tar".

"Tar" in such a case acts like "Tyvek" or other membranes which prevent 'liquid water' from penetrating because of 'surface tension' or other chemical characteristics of liquid water...BUT will always allow gaseous water to pass thru and penetrate because the molecular compaction of the membrane materials is larger than gaseous water molecules.

All I am asking is a reasonable and scientific explanation as to WHY 'tar' foundations can remain watertight and yet remain 'damp' from gaseous water infiltration as I know they are subject to.

If you do not know, that is fine.

But, please, do not try to obfuscate the fact you may not know by trying to divert the question into some kind of false accusation about my motives (knicker or knots) or any diversion against my question because you have no answer.

I am completely willing to be instructed and corrected by you or any one else, but not bull**** let's get to the point, shall we?

If you know better than I, then explain why and how so I can be a better person as well as a contractor.

So far I remain merely buffaloed by your responses.

Over to you....



12:51PM | 05/06/04
Member Since: 11/06/02
1280 lifetime posts
It is your premise that gaseous water vapour wioll pass through where liquid water will not that is in error. Correct that assumptioin and every thing else falls into line.

Want to get practical in terms of the original question? I'm sure we're both here to help folks out more than to start arguements.

What ahs always worked for me on typical residential work in even a wet clay soil is this.

patch any open sores or honeycomb in the crete with hydro stop or mortar.

seal the concrete wall with Thoroseal.

Then roll on or spray on an emulsified asphalt.

Be sure there is a good perimeter drain with gravel and fabric.

Backfill with inch minus

this will keep a cellar dry unless the water table drives water up under the slab, but we are talking about the wall here.

Excellence is its own reward!


06:12AM | 05/09/04
Member Since: 01/28/03
693 lifetime posts
Piffin, sorry for the delay in responding.

Away at a code training seminar all week.

I would have to repsectfully disagree with your assessment that damp-proofing and water proofing are one and the same, and that all materials used to damp proof and block gaseous water from penetrating the foundation.

They do not.

Foundation 'tar' coatings can be one such material.

It behooves anyone concerned about basement waterproofing and vapor proofing to do the necessary research to assure they are getting what they pay for and expect.

And one should not assume that all materials for damp and waterproofing serve the same purpose when they do not.

It is not 'error' or even preseumption that gaseous water can pass thru some membranes and coatings and yet disallow liquid water to pass and vice versa. It is well established fact.

In fact, this is well established and known science and vapor technology and the documentations for their consideration well established by researchers, engineers, architects and model code administrators.

My concern in offering this advice is not to start arguments but to offer caution when establishing the water as well as vapor proofing potential of basement walls.


08:24AM | 05/09/04
Member Since: 01/28/03
693 lifetime posts
Here is a helpful link in establishing some defintional and functional differences between 'dampproofing' vs 'waterproofing' and the permeability differences between some membranes and coatings:

But back to the original question:

If you want the best 'dampproof' coating, get the coating that has the lowest permeability rating.

By 'waterproofing' one's basement, one will almost assuredly make it impermeable to vapor transmission as well.

Not so with dampproofing alone.


05:17PM | 05/09/04
Member Since: 11/06/02
1280 lifetime posts

"By 'waterproofing' one's basement, one will almost assuredly make it impermeable to vapor transmission as well."

That's what I said

Excellence is its own reward!

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