| The reason the joists are covered in mould is down to history!
One: The house was flooded at some time, a leaking roof or burst pipe.
Two: The house was left empty for probably a year or more and during this time the joists reached the same low temperature as the rest of the crawl space. Result. Mould.
I would guess the second is most likely.
The solution is: Mould dies when it can no longer feed, eat the cellulose in the wood, or when it is deprived of water, both of these are unlikely to happen. Due to the high humidity in the area and lots of wood to feed on.
The recommended solution is professional cleaning - this will cost a lot.
Trying to dry out all the humidity in the world with one dehumidifier, will never work!
Water vapour has a built in tendency to equalize but, look at the sky all the cloud shapes are different, the same patten is repeated on ground. The moisture is forever moving from one warm place to the next cold one, from one area of high pressure to the next area of low pressure..... trying to equalize and never succeeding.
Unless you have a sealed room, humidity can only be controlled never beaten. Sealing the crawl space and the floor above plus the ground below is too expensive.... I guess.
I do wonder who inspected this house prior to purchase
and if they are liable in law. Certainly, a lot of insurers do not include mould damage in their policy now.
OK So, you have all the gear and winter will come soon enough.
Here is a bit of information that seems to be missing.
Dew Point Calculation Chart (Fahrenheit)
%RH AMBIENT AIR TEMPERATURE IN FAHRENHEIT
20 30 40 50 60(70)80 90 100 110 120
90 18 28 37 47 57 67 77 87 97 107 117
85 17 26 36 45 55 65 75 84 95 104 113
80 16 25 34 44 54 63 73 82 93 102 110
75 15 24 33 42 52 62 71 80 91 100 108
70 13 22 31 40 50 60 68 78 88 96 105
(65) 12 20 29 38 47(57)66 76 85 93 103
60 11 19 27 36 45 55 64 73 83 92 101
55 9 17 25 34 43 53 61 70 80 89 98
50 6 15 23 31 40 50 59 67 77 86 94
45 4 13 21 29 37 47 56 64 73 82 91
40 1 11 18 26 35 43 52 61 69 78 87
35 -2 8 16 23 31 40 48 57 65 74 83
30 -6 4 13 20 28 36 44 52 61 69 77
From the above you can I've put brackets round 70 degrees farenhite and 65% humidity
and when you go to where they cross you find a dew point of 57 degrees farenhite. Any surface temperature colder than 57 degrees will have condensation and get wet. Now you can really monitor your crawl space without going down there.  |