Breathable Walls

My opinion is probably worthless...but

Just because someone else hasn't done it right...that's no reason for you to join in that process...the road to hell is in that direction!

The pragmatic answer is 'What are you being paid to do?'

Me & Mrs Cat just papered a wall...cutting the second strip we forgot to allow for patern matching...we had a choice ..patch in 6" at the bottom (it will be hidden by a filling cabinet) or re-do that strip...

We re-did it.

(I reserver the right to be of no help whatsoever )

Del

The local authority Planning Office that is supervising the project will be able to give advice. They will have either a specialist period buildings conservator or access to individuals who know about these things. It's worth a couple of phone calls to them, indeed if the project Architect doesn't know what to do.

This is new territory for me so let me try to re-phrase the question. You are concerned that the low water vapor permeability of the exterior finish will cause the internal humidity to increase and compromise the historically correct internal finish. If this is correct, my advice is 1) transmit your concerns to the contracting agency and ask for a decision 2) monitor the internal humidity with an accurate hygrometer, and report any abnormal humidity increase 3) Recommend the use of a dehumidification system if internal moisture appears to be a problem.

I believe your concern here is real. The exterior, being less porous, will cause the internal walls to sweat and hold moisture, as the pH is drastically different than the original mortar. Otherwise your interior walls shall have lime growth internally, into your walls, and trim. The air quality will be horrible, in short order.

Maybe a good water sealer is in order, before you coat the inside with anything, but I would go another route.

A roll of black paper and new horse hair will not stop moisture damage and will degrade over time under the wall finish. You need the moisture barrier of Tyvec with adhesion to bind and seal the interior wall and masonry, so further degradation does not occur. Only then, can you guarantee the interior from leach of the mortar lime.

Speaking as a person who has finished several homes which qualify for architectural and historical preservations, it seems most folks do not understand what preservation really means. It does not mean using the exact materials to re-construct a building; on the contrary, it usually involves the use of advanced materials to restore the durability, as well as retrofit the damages. All this while attempting to re-create the luster of the building, during the era it was prime.

I assure you, my associates have never used a hatchet, pieced together mismatched studs, gone out to the blacksmith and made our own nails, in order to be historically accurate, under the finish layer.

Spray it all with plastic and be done with it. It will form a binder and stop air from deteriorating the brick joints; indeed, it will probably be stronger than any other approach and should internally re-enforcing. It will hold a screw and can be agitated or impregnated with mesh for a final coat of masonry.

Wallboard is useless in these situations, as the cardboard will mold eventually and the time and effort is wasted in just a few years. I have had lime grow right through the tape joints and destroy moldings, unless the moisture barrier is properly maintained.

Contrary to popular belief, walls do not need to breath. Moisture control can and should be achieved via HVAC systems and de-humidifiers, to control the intermediate humidity.

A well known Florida historical builder who trained me for such eco-development was capable of sealing the exterior walls, while cooling a vaulted 26 foot ceiling, at a savings of 65% of energy consumption. Most notably was the double insulated window sash wrapping, electrical outlet weather seal barriers, improved insulation techniques and caulking of all plates, base boards and Crown moldings, directly to the sealed walls and subflooring.

This quality system eliminated any "breathing" at the base plates and lowered the monthly energy bills of much larger additions, considerably; over the smaller homes we started with. We doubled home square footage and lowered the energy cost at the same time. Unfortunately, not everyone gets it, until after they see the bills arrive and they save a fortune. Humidity and air quality control can be achieved simultaneously, when the smell and vapors of older building materials are removed from the living space.

The bad news: Gypsum is radioactive.

The exterior walls my friend has designed recently, have no wallboard; whatsoever. They are completely EPS foam and Steel studs with a layer of Polyurea, instead of wallboard. Zero mold, period. Flat durable walls. No call backs for warped studs.

Just shoot the brick wall with a layer of Polyurea and then attach a layer of EPS foam. You can stud in between supports and re-coat everything again or finish with alternative plaster-like materials. No more rat urine smell.

The system removes the chances the interior of the EXTERIOR structural walls can be easily damaged by the furniture installers or by water damage. They never mold, if sealed properly and can be re-textured within a hue of color, years from now, as the primary color ingredients can be slide ruled, as the the degradation of the "top coat only, color component". (Polyurea is gray in color. You'll want to decide on a color for the 1/16'' skin coating. It does cost a bit more to add a color coat).

Polyurea can also be sanded and painted, just like any wall board. It may be final coat finished, just like the methods they used to screed plaster, but it is easier to spray. It is very durable. (You will have to use screws instead of nails for the pictures and wall hangings and do not try to punch through the walls). At 1/2 inch it becomes ballistics rated and will stop small caliber bullets. It does wonders for re-enforcement during a hurricane, when the neighbor's loose bricks, roofing shingles and lumber start to break free and fly through your walls.

One has designed systems for Polyurea to be sprayed over steel roofing, with amazing results. One foreman type with a helper or two, can easily re-seal an existing chain drug store built up or rubber roll roof in under four hours and the welt is good for well over 25 years. It sticks to wood, aluminum, steel and other types of plastics, without any problems. It can be shot over radius walls and non-standard surfaces much easier than chopping wallboard or applying mastic.

For instance, my plan is to cold roll the roofing shingle pattern into thin gauge steel, (much like the super gutter system), so it looks like regular roofing from the curb and then shoot polymer over the entire roof; so it remains one solid piece. All fasteners are hermetically sealed against galling and corrosion. (If a storm takes this style roof off, or blows through walls with flying debris and studs; we have bigger problems than home repair anyways).

Many of these older structures are not healthy, because of the composition of the old wall and roofing treatments. In fact they are carcinogenic and respirators and over-clothes should be used to eliminate any inhalation of the dust. Much of the dust can contain rodent urine. Disposal of the broken plaster is considered hazardous wast and should be disposed of properly. Many times asbestos was included into the mixture. Ask your client if the "health and breath ability of the building", includes cancer or lung infection prevention.

When you consider removing over 91% of flammables over traditional roofing and wall board systems, the FIRE safety factor is very desirable. Polyurea is fire resistant and EPS foam insulation burns at 160 degrees higher flame temp than wood, let alone wallboard.

If you want the home to breath, open a window; not a horse-hair, plaster covered masonry wall. Seal it all up and start new on the inside.

Your energy consumption will be much less, as radiation cooling and thermal bridge heating will be eliminated, or at least controlled; (since you may not have six inches of wall thickness of EPS foam to eliminate the thermal bridging, entirely).

Hi,

My self is a structural Engineer It is advisabel to go for the same mix on interior becouse Following resiona

1. When you applay NHL the rate of hydration will be more.
2. Expanshion of NHL and cement morter is not same.
3. Jointing betweeen NHL and cement morter is not effective in long term.

OK,

Differences of opinion abound! The general principle is that the plaster is a 'sacrificial' coating that protects the brick substrate, and it should be weaker than what it protects. The brick and morter is liable to crumble and crack because the cement plaster is too strong, rigid and unflexable, therefore any stress from movement would effect the brick and mortar base before it affects the plaster, and like a sand castle that is robbed of moisture, it would collapse eventually.

Therefore I am leaning towards the weaker mix for the interior and a good escape clause in the contract. What do you say to this?

The way I look at it ..the coating on the outer wall is to keep moisture out (but it won't alltogether..especially rising damp etc)

The inner coat has to let out any moisture that does get in. Therefore the inner coating can be as porous as you like...it mustn't be less porous than the outer layer.

Dunno if this is right but it sounds good to me

Spray it with a layer of structural foam and / or a Polyurea Polymer Plastic Coating, then finish with any material of choice. By strengthening the core structure around a layer or re-enforcement and possibly improving fire rating, R-Value, termite resistance, and sound proofing; all at the same time. You can paint and finish it like any other stucco or push flat panels into the foam as it sets, for backing boards and apply more stucco. This sandwich will improve the wall integrity and can be used in between supporting studs and columns.

You may bind the interior materials and save the structure from further decomposition, while controlling humidity to at least one of the surfaces you are trying to preserve. Polyurea sticks to almost anything. It is very cool stuff.

I'd probably be satisfied as long as more than 50% of an old wall, as an improvement over re-creating the same problems or using materials which may alter the pH of the stucco and mortar.

Seal it, first.

This insulation works well also, as it can be shaved and sculpted prior to or after preliminary Polyurea coating:

http://www.tigerfoam.com/

My associate and I are rather fond of the idea of shooting polymer coat over the brick or block, shotting a tiger foam layer or using EPS and fasteners into the masonry, sculpting and then final coating with more polymer.

The process is very similar to the original method of lath and plaster, as the art of the application process is an important regiment.

Truly; the best part is the materials are bonded and rated by the manufacturer, so you'll have a chain of liability in case of product failure. None of the chemicals actually require any special mixing.

Polyurea is a two part component and is heated in the hose merely for viscosity and fluid movement while being sprayed. It does not require any calculated or precision mixing, as the machinery to shoot it does this for you, and therefore covers the application crew from fault during application.

Therein lies the liability rub; so to speak.

This quality control over materials is THE key factor, explaining why the mortar in the bricks and masonry in Frank Lloyd Wright's buildings are a failure; as he did not require assurances of the integrity of the ingredients used to bond the materials he chose. They were mixed, by the constructors haphazardly to save money and spread materials beyond the intended coverage. They cheated.

Frank failed to certify the bonding agents during construction and his buildings are a catastrophic expanse on the Department Of The Interior, as a direct result.

Not to mention the poor insulation values. At the current price of home heating oil, they are unsustainable as publicly used historic sites and bankrupt the endowments decades early.

The endowments will be only capable of sustaining minimal use, unless modern techniques are employed to preserve the quality of the structures; improving efficiency and structural integrity substantially. There is no bottomless pit of money to continue using old, inefficient building practices on historical monuments.

We must look beyond the short sightedness of the "establishment", if we are to preserve anything of such value for future generations to enjoy, study and learn from; without planned obsolescence destroying the feasibility of such noble effort.

In my humble opinion, it is truly a crime, when an ill informed or biased customer/ specifier forces ignorant or ill conceived materials choices, based on antiquated technologies, purely because he or she may harbor inside arrangements with "the good old boys" who are stuck on using poor quality materials, at the cheapest labor costs, to maximize profitability and spread the 'tips". These fine people are continuing to cheat the end user, in similar failure "fashion", as Frank.

Most of the Wright buildings, as my reading of late has explored, are run by temporary elected administrators, who are unable or unwilling to plan long range construction projects past their term of administration. This issue, stands as the worst possible contingency on provisional retrofitting of older buildings, as it deprives the intended user any choice over the methods used to preserve the endowment.

Who wants to complete a previously started renovation project, at a historical sight, employing new technologies, during a new high profile term as director of preservation of a historical asset, when one does not have the "inside deal" on parts and supplies with family and friends included in the bidding? Our current system is designed to waste money and resources, not preserve them.

The incentive for employing quality repairs must start with the intention to desire quality for the long run, in and of itself. Not be controlled by redundant and costly, (and very profitable for the cost plus contracting companies), renovations or reflection of planned obsolescence; every four years of office and budget allocation.

Works of art and design deserve quality restoration and preservation, with the long term in mind and a nod toward the Washington's Hatchet dilemma. At what point it becomes something else, is useless criterion if the cost of preservation over the term of expected use, is unsustainable. Value should be decided in the eye of the taxpayer or the one who intends on sustaining the entire building, avoiding recurring waste.

The legacy we are on the road to leave others is obviously a failure, much like Frank's endowment planning. Unless, of course, we are truly on a road to recreate more of the same failures for future generations to contend with.

I doubt your internal coating is at much risk. The level of disagreement seems to be based on the "this worked for me" principle, rather than observations of similar situations that have caused problems.

Now, I don't know where you are based, but the usual principle is that vapour tends to penetrate from the warmer side to the cooler. If you are in a warm climate and the inside is being cooled and dried, you have nothing to lose by using a porous inner coating. If you are in a cool climate, and the inner side is porous, the vapour from inside will penetrate into the brickwork; if the outer surface is impenetrable, a moist layer will form at the boundary; there will be dendritic growth, but this is unlikely ever to reach the inner surface of your wall. What might eventually happen is that the outer surface may separate from the brickwork, damaging the brick surfaces in the process.

Having been pointed at possible problems, what is the reality: I live in a medieval house that was incorrectly reclad with impenetrable Portland cement about 40 years ago. When we had some works done shortly after we moved in, our local building's inspector said we should leave it as it is, and monitor the situation, and that the timbers were the most susceptible parts of the building. So what has happened? The observable effect is that we only see rising moisture levels when the cladding cracks (this is caused by the flexure of the timber frame building), and we are able to patch these before they reach problem levels. BTW some of our internal surfaces are lime plaster and hogshair, some others are cowdung, hogshair cowhair and horsehair; none of these have shown any signs of problem; however, there is a cavity of sorts (except where the wall is full of 17th century rubble)

This is just one experience, of course, but on a structure that is usually regarded as much more susceptible than what you are dealing with. So my inclination would be to use original materials if at all possible, and if necessary advise the owner to take out insurance and monitor for problems.

I thank the guest for the analysis of the problem and his/her advice is the route I have been pursuing for the last week. I am in the Baltics where it is hot in the summer and cold in the winter. I have been fortunate to find a local, medium sized cement company that was thinking of venturing into the restoration plaster business and this project has piqued their interest enough to jump in right away with mixing the sand and natural hydraulic lime that I want and all I have to do now is provide the pozzolan to their mix and I am away and running - I think. Saves over or under ordering from other sources further away and keeps the air cleaner by ''going local'' and using a surface that will absorb CO2 to carbonate as it hardens. If all goes well I may even help in the marketing of it. Funny how things work out if you dig a bit deeper into a problem.

I expect your winters will be drier but colder than in the UK. A Finnish civil-engineer (or even a suitably experienced builder) would be better placed to comment than I. Nevertheless, I personally wouldn't foresee any problem unless moisture is being generated inside the building and the boundary between the brick and the outer surface of the bricks reaches freezing; that should not happen if the building is adequately ventilated when unoccupied.

You don't want to put foam plastic on the interior and just coat it with polyurea to paint, or acrylic coating. Foam plastic on interiors would need to be covered with 1/2 gypsum wallboard. See IRC R314.4 and IBC 2603.4. Read and understand them. If you need to, hire a professional fire protection engineer to work through the subject with you. Neither polyurea nor acrylic coatings qualify as 15 minute thermal barriers. They cannot pass the ASTM E119 test cited in the building codes. Do not confuse ASTM E 84 flame spread index under 25, which the coatings manufacturer may have, with the 15 minute thermal barrier requirement. Also do not confuse the fire tests for exterior use of foam plastic given in IBC Chapter 26 for 15 minute thermal barrier tests. They are nothing alike. Also contemplate the shockingly short prison sentences of 10 and 15 years, mostly suspended, given for the 100 deaths in the 2003 Station Night Club fire in West Warwick, RI, from improperly protected interior foam plastic. Save a life, including your own.

To the suggestion for Tyvek interior use: it is not a vapor retarder. It was purposely designed by Dupont to have high vapor permeance. See Dupont Tyvek literature.