Porch damp/paint question.

grizzly1911

Elderly relative.

A late 50s house with a flat roofed porch on the right of the property. The right hand side is effectively an extension of the original side wall.

The outside opposite corner had a vertical pole to support. Originally had a concrete floor with quarry tiles.

Later it had a glazed wood porch frame in the two open open sides, pole removed. The two inside walls were plastered and then painted successively

This was later replaced by a double glazed unit and the flat roof recently re-felted so it is and always has been weather tight since "filled in".

The right hand wall whilst painted with a vinyl matt emulsion was fine for many years.

Over the last 5 years or so the paint has started to flake off from the outside right wall from around 6 " spreading up a further 12" . I presume this is due to a small amount of damp. It is not condensation from inside and the damp course doesn't appear to be breached and there is no visible ingress from an overflowing gutter or similar.

There are no obvious signs inside the house.

Some form of damp treatment has been applied inside and then repainted but it is still flaking.

I want to try and tidy it up. Will remove all old and flaking paint to see if anything comes to light and then tidy it up.

Any ideas on what can be done a "good patch".

Would eggshell be better than vinyl emulsion?

nickj_2

is the wall you are talking about outside or inside , if outside then emulsion is an interior only paint , if it is exterior i would scrape down the flaking paint and seal with a stabilizer and then paint either with dulx weathershield smooth masonry paint or sandtex

ifr it's inside then you need to sort the problem out , if it's just a temp job then get some damp seal and then paint with emulsion or waterbased eggshell

grizzly1911

MrInvestor wrote: »

Does it have a DPC? If there is no visible sign of damp, it could be that the paint you have used has had a shorter life than if it were used in an internal heated environment. what did you paint onto? Brick/block/plaster? Sorry I lost track of what it was.

I painted the interior of my garage a few years ago - dense breeze block walls - with an external grade paint containing silicon. It worked fantastically and have had no problems to date (3 years later).

There was even a small amount of blockwork below the DPC exposed to the front of the garage where the floor slopes slightly that used to become damp but since painting, it seems to have trapped it in the blockwork to escape to the outside instead.

Yes it has DPC and it was painted onto plaster.

grizzly1911

nickj wrote: »

is the wall you are talking about outside or inside , if outside then emulsion is an interior only paint , if it is exterior i would scrape down the flaking paint and seal with a stabilizer and then paint either with dulx weathershield smooth masonry paint or sandtex

ifr it's inside then you need to sort the problem out , if it's just a temp job then get some damp seal and then paint with emulsion or waterbased eggshell

It is an inside wall now, but outside of the normal exterior of the house under a flat roof. It would have been an open porch with a standard facing brick under a flat roof.

Can I query why you suggest a water based paint, would a solvent based paint be better?

nickj_2

grizzly1911 wrote: »

It is an inside wall now, but outside of the normal exterior of the house under a flat roof. It would have been an open porch with a standard facing brick under a flat roof.

Can I query why you suggest a water based paint, would a solvent based paint be better?

you can use water or solvent based paints if you wish but it is the surface preparation that is the most important thing -

grizzly1911

MrInvestor wrote: »

Ok, it sounds like you might have moisture in your plaster from the outside. Is the wall made from two leaves of brick/block or just the one (ie 100mm thick)? If it is just one, you will stuggle to keep the moisture out.

If the wall is 200-225mm thick, then it is likely to be two leaves of brick against each other. If there is excessive moisture/water on the external face, the moisture could be working its way through the mortar to the inside face.

If the wall is thicker than 250mm then it most likely has an air cavity between, which can also act as a break for moisture. If this is the case, check that there are at least a few air bricks and that they are all clear of obstruction. If you cannot see an issue with the airbricks, it could be that the brick layer did a poor job and slopped the mortar across the cavity causing water to run down the mortar onto the internal leaf.

The only other thing I can think of might be that your window cills or roof overhang does not have a drip to stop the rain tracking back to the brickwork.

Let me know how you get on with the above and I'll try to figure it out with you if you still don't have any luck with your analysis.

Will be another week or so before I visit property again will double check then.

Thanks.

grizzly1911

MrInvestor wrote: »

If the wall is thicker than 250mm then it most likely has an air cavity between, which can also act as a break for moisture. If this is the case, check that there are at least a few air bricks and that they are all clear of obstruction. If you cannot see an issue with the airbricks, it could be that the brick layer did a poor job and slopped the mortar across the cavity causing water to run down the mortar onto the internal leaf.

The only other thing I can think of might be that your window cills or roof overhang does not have a drip to stop the rain tracking back to the brickwork.

Let me know how you get on with the above and I'll try to figure it out with you if you still don't have any luck with your analysis.

Update.

Cavity wall with gap and DPC two bricks higher than footpath.

Flat roof looks good, with lip althe way round apart from gap where it drains into a hopper above said problem.

The down pipe just allows run off onto the pavement, away from the wall, and at sometime has been dislodged slightly. One of the mounting brackets for the pipe is broken.

It wasn't raining, surprisingly, at the time of my visit but it is possible that rainwater is going into the hopper but it isn't all going down the pipe with some going down the wall. There is no staining or visible signs of this.

The mortar on the outside close to the level of the "damp" area is perished with some small holes 5mm in it. How it is transferring across the cavity I know not.

I will remount pipe, dig out and re point in the immediate vicinity of the holes and redecorate, using some damp seal first. Fingers crossed.

tony6403

Flaking paint is not necessarily a sign that you have damp.
To save me time with typing I have nicked an extract from elsewhere to give some possible causes
What Causes Paint Cracking or Flaking?

• The use of low-quality paint, resulting in inadequate adhesion and flexibility
• Oil-based paint applied over latex paint
• Paint was spread too thin during application
• Poor surface preparation, especially when the paint is applied to bare wood without priming
• Paint drying too fast due to environmental conditions
• Paint becoming brittle with age, failing to expand and contract with temperature and humidity changes
• Extreme cracking, sometimes called "alligatoring," caused when a second or third coat of paint is applied before the previous coat dries completely, or when the undercoat is incompatible with the finish coat

Some food for thought there.
Don't go looking for air bricks in the brickwork above dpc. It is not common practice to ventilate cavities .Cavity trays are used above dpc level. Air bricks are to ventilate suspended timber floors and will be below the dpc.

tony6403

MrInvestor wrote: »

Any air cavity should always be properly ventilated, whether by traditional clay air bricks or, more commonly these days, with weep vents. The 'air bricks' used to ventilate under beam and block floors are actually telescopic ventilators, not air bricks in the traditional sense.

Where on earth did you get this nonsense from?
Cavities are NOT ( except in some types of timber wall constuction ) required to be ventilated.
I have worked on many properties and cannot recall seeing a ventilated cavity. We have arranged for extensions to be built - drawn up by architects and approved by building inspectors -and have never ventilated a cavity.
Weep vents are used above lintels and also drain out any drips that may come down the cavity and hit a cavity tray; they are not for ventilation.
Has it occurred to you that cavity wall insulation, a requirement under building regs. , often fills the cavity ?

tony6403

You clearly will not accept my telling of the facts.
Here is an extract from " Professional Engineering".
The cavity in modern cavity wall construction is not ventilated.
There are tiny weep holes in the outer brick leaf at the bottom of the cavity but these cause negligible air movement in the cavity. The only air movement is that by natural convection and is minimal.

Have a look at any property built after 1940 and you will be hard pressed to find an air brick above dpc. Even those before that date seldom had ventilated cavities.
If there was a need for this it would be a requirement under Building Regulations - it is not.
It seems that ALL bricklayers employed by ALL the major housebuilders are according to you using bad practice.
Please make sure that you actually know your subject before trying to advise on here.

tony6403

MrInvestor wrote: »

Yawn.

If you really want to get technical, the lasttime I checked, ventilation of voids was not an area covered by Engineers?! Byproviding weep holes you are ventilating the cavity. Generally when you have alimited amount of something ...you still have that particular something.

REPLY Here is what building engineers do
By definition, a Building Engineer is a professional who designs, constructs, evaluates and/or maintains buildings whose work includes both technical and management processes by which buildings are designed, constructed, renewed and maintained.

You also put a number of weep holes abovelintels and can even see them placed at floor levels above GF. In actual factthese provide a fair amount of ventilation - enough to prevent a build up ofmoist air within the cavity.

REPLY Wrong again. Not for ventilation.



Most pre-1940 houses have air bricks. If youfind a Victorian house with a damp problem, chances are the air bricks havebeen removed or blocked up because some idiot builder said that they weren'trequired ...and obviously Victorian houses have no alternative ventilationprovided by weep holes or open perp joints.

REPLY Victorian houses did not have cavities. An extract from a council website : Cavity walls are generally found on dwellings built after 1932. Before this, the main form of construction in the UK was the solid masonry wall



Again... you are missing the point that weepvents or clear perp joints DO provide ventilation. It's not an air tightcavity is it...?

REPLY Fire regulations provide for just that. The cavities are sealed at the top to prevent fire spread.

Interesting as previously you stated that...



Firstly Building Regulations reads that it isgood practise that...



So how many walls have you actually built?!One? Two? Have you built any in the last 10 years? Everybody uses rigidinsulation boards in new build cavity walls these days. It's quicker and easierto install saving the Contractor money overall. Only amateurs use flexibleinsulation batts(which is the only type of insulation used in full fillcavities). Full fill cavities were all the rage in the 80's but often led todamp failures so have been left in that era.

REPLY I am presently sat in an extension which I built myself - without ventilating any cavity. I have built others. Not one house on my street has a ventilated cavity. My friend is currently working fitting flood prevention systems. I asked him tonight in the pub and he has never found a ventilated cavity. He works all over the country.

So maybe you not as informed as you think onthe subject.

REPLY Apparently somewhat better than than you are.

I originally posted my comments in the hopeof possibly providing a solution to the OP - which is difficult as I have notseen the wall myself.

REPLY Commendable but no advice is better than bad advice.

You however are just rude and ill-informed.Therefore I will not be responding to anymore of your posts.

REPLY No. I am rarely rude.
I only respond to posts where I have the necessary knowledge /experience.
Disagreement is not rudeness.