Rising Damp Sydney - Sub Floor Fan Review - The Dangers!
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- Опубликовано: 8 апр 2018
- www.RisingDamp.Sydney
Read this description if you want more detail.
Here is a video about what rising damp does to a house and how installing sub floor ventilation can actually speed up the damage to your house dramatically!
Water does NOT damage masonry, salt does. As salt dries in the masonry, as the salt crystals grow, they push apart the bond between the sand and cement particles. THIS is what causes the damage to the masonry.
How does salt water dry?
Evaporation!
What are you doing when you install fans?
Speeding up EVAPORATION dramatically.
What's left over when the water is gone?
Salt Crystals.
To give you an idea of how much force salt crystals have, it can turn 60MPA concrete to dust over time. Your bricks are no where near 60MPA, a standard house slab is around 25-30MPA.
*You may need some kind of ventilation BUT you CAN mitigate the damage that may occur.
You ONLY need sub-floor ventilation for 3 things.
1. Removing damp smells before they come up through your floor boards.
2. Helping to control a mould problem.
3. Helping to prevent the timber under your house from rotting.
If your house is built on clay, by drying the subfloor out too much with fans you can cause the walls of your house to crack. Clay expands when it is wet and contracts when it dries, kind of like breathing lungs.
*** The point of this video is to show that sub-floor ventilation fans DO NOT STOP RISING DAMP. Visit my website to learn more www.RisingDamp.Sydney
Rising damp, mould, damp smells and rotting timber are all very closely related problems caused by moisture under your house but the solutions for each individual problem can be very different.
If you DON'T have a salt issue there then you MAY NOT get damage like this. I have also been to houses that have had fans installed for more than 10 years and they do not have this kind of damage.
If you do need to install fans then keep an eye on the subfloor walls to see if you have any damage occur.
If there is damage occurring over time you can get some sand & cement render and apply it to the subfloor walls with your hands (not real pretty but no one will see it) and the render (you can just use pre-mix sand and cement from your local hardware store) will be a sacrificial layer on the surface sub-floor walls and piers.
i.e. The sand and cement render will incur the damage instead of your bricks and mortar.
By putting a mortar layer ON TOP OF the subfloor walls and piers (as a 5-10mm coating) the salts will crystallise in the NEW layer you have ADDED instead of in the original substrate of your house. Over time this layer may deteriorate and you may need to reapply in places. Doing this will mean you don't get any structural damage as seen in the video above because the salt is damaging the sand & cement layer instead of the bricks.
Good video dude 👍🏽👍🏽👍🏽
Shite. thanks mate, will steer clear. My takeaway is the damp-ish foundations/bricks are inevitable and probably okay... our home is 105yrs old and on clay soil. We had our rising damp treated above floor but was looking into this as we have rotting joists where they meet the wall. Is replacing this with treated timber my best bet? ventilation will be tricky as all the walls go down to the ground - ie i need to do each room
So what’s the best way to keep ur subfloor floor ? I got bad ventaalrion subfloor wet termites u name it
Yeah if you have termites then you may need some kind of ventilation.
If you don't have a salt issue there then you may not get damage like this.
If you do need to install fans then keep an eye on the subfloor walls to see if you have any damage occur.
If there is damage occurring over time you can get some LIME MORTAR and apply it to the subfloor walls as if it was render with your hands (not real pretty but no one will see it) and the render (you can just use pre-mix sand and cement from your local hardware store) will be a sacrificial layer on the surface sub-floor walls and piers.
i.e. The lime mortar "render" will incur the damage instead of your bricks and mortar.
By putting a mortar layer ON TOP OF the subfloor walls and piers (as a 5-10mm coating) the salts will crystallise in the NEW layer you have ADDED instead of in the original substrate of your house. Over time this layer may deteriorate and you may need to reapply in places. Doing this will mean you don't get any structural damage as seen in the video above because the salt is damaging the lime mortar layer instead of the bricks.
Same problem also probably starting in the next few months.
How did you find out if the soil head salt in it
You can get it tested, it's the accumulation over time that causes damage. There may be a lower salt percentage in the soil but very porous bricks which absorb and homogenise moisutre faster therefore they get damaged faster. On the other hand you could have high salt content and very dense bricks that have a slower absorption rate which means a lower amount of damage from salt accumulation. It's not so black and white.
Thank you mate,
Would econofans that detect humidity fix this?
The fans do the same thing regardless of the way they activate.
Sometimes you do need fans.. but installing fans for the purpose of curing rising damp is not the solution.
Fans are used to eliminate damp smells, mould and rotting timber. Fans do not cure rising damp.
Check out my website www.risingdamp.sydney
This is rather pointless. What should people do? Don't just scare people out using sub floor ventilation, help them understand what options there are.
People can call me for the options, that is the point. ;)
What am i missing here? The rising damp seems to be main culprit no? The damp proof course was not adequate to begin with? I dont see how the fan promotes rising damp...
The damp course was installed about 100mm below internal floor level as per regulation, so below the internal floor didn't have a damp course. If the bricks are in wet ground.. they get wet.. then the brick above gets wet too.. then the brick above that one... with the moisture from the ground comes diluted minerals.. if you dry the masonry, more water comes from below to replace the evaporated water and so on.. speed the evaporation up and you in increase the water coming up the bricks from the soil. Increased evaporation means more water passing through the wall to the evaporation point which means a greater accumulation of salt in the masonry. The salt turns to crystals as it dries and push apart the bonds between the sand and cement, and turns it back to dust. Go and look under 30-40 old houses.. you'll see near vents, sub floor fan exit points or access doors etc that the mortar is more likely to be missing there. This video is an extreme case, the worst I've seen.
@@jasehere4589 interesting mate thanks for explaining. Does it then also depend on salinity of soil? I guess its fair to say some areas would contain more salt? I was contemplating potentially installing some fans. I suppose fans dont dry out the ground enough either to stop or reduce the rising damp
@@united3689 within about 15-20kms of the sea the salt is higher. You only need fans if you have damp smells, rotting timber or mould. Fans just evaporate the water below floor level which makes it look like it's fixed but it's not. Rising damp is about salt, water and evaporation. It's OK of masonry is wet (in the right locations) water doesn't damage masonry, drying salt does. If you have masonry which is being damaged under the house then you can put 5mm of a sacrificial layer off lime mortar on it which will save the walls and piers. Sometimes fans are needed, i try and avoid them when i can. Having said that we installed 3 this week. It's situational.
@@jasehere4589 Thanks Mate. Is that means passive vents are enough and safer than electrical fans for the subfloor?
@@jasehere4589 did u instal eco fans around $250 for a. Pair or just a $30 exhaust fan will do the. Job. My house is wet timber rotted snd I found termite outside near the house beside the house the timber gate . I’m getting t a termite treatment soon as soon as my subfloors dry .. I’m thinking of adding fan and as the guy in video mentioned on comments let it extract air not blow it in