Porous Roof Tiles, Sealing Option

[JohnE]

After the heavy rain on Friday night I went up into my loft and to my horror, found that the rain has seeped into the whole of the roof space. All the felt is soaked with the rain dripping through the felt onto the loft insulation, and the rafters and joists are wet. The tiles look like concrete/clay and presumably have become porous. The house was built in 1964. Last summer a number of houses in the area has their roofs cleaned and spray sealed by a roof sealing company. I can't afford to have the house retiled so my questions are as follows:

1. Does this roof sealing (cleaning and spray coating) work
2. Any ideas roughly how much a 3 bed semi roof would cost to be treated
3. Am I correct in thinking that the problem is porous roof tiles.

 

[Alastairreid]

hi, i will answer your question with a question.

are you sure this is not condensation?.
how much insulation do you have in your loft?.
does your loft have ventilation? ie tile,soffit, vented ridge.

you would not normally get a cataclysmic failure of your roof covering without you noticing water ingress through your ceilings first.

i mean how often do you actually go in your attic?
bearing in mind we are in the winter months now more humidity in the house, heating on windows closed etc.

your attic has to be well insulated to stop the warm humid air getting to your roofspace you also require airflow in your attic......i really dont think this is whole roof water ingress...condensation would be mor than likely.

the question about painting /sealing your roof.....as you stated the houses around you have been re-roofed recently.....why !..... because they have came to the end of their lifespan.
you wouldnt paint a rusty car or crumbling wall in your house.

this roof covering looks good for 5 minutes, i personally think its a waste of time and money.
i have been on loads of roofs where this stuff has been used and in my experience if the roofs past its sell by date the paint will serve no viable purpose.

last painted/ treated roof i was on the guys done more damage than good.
the roof has to be sound no broken flaking tiles, ridge tiles secure and no loose pointing. and it cost her £800.

my advice........vent your attic and save up for a new roof.

 

[^woody^]

Tiled roofs don't need sealing. Tiles generally last for 60 years plus.

If water gets past the tiles it is kept out by the felt. Only if the felt is ripped or holed does water come in.

If you have wet felt and rafters all over as opposed to a single place, then you have condensation.

Condensation is more likely after rain as the rain will cool the roof thus lower the dew point and allow condensation to form

Just be happy that you were not suckered into this pointless coating like the neighbours were

Read recent posts for how to deal with condensation

 

[JohnE]

I really appreciate your advice, many thanks.

I suppose I could be wrong but I can't believe it's condensation. I really hope it is. Can condensation really soak a joist right through and saturate all the felt? I've got a fair amount of insulation up there and I suppose, as a 1964 house it's not particularly well vented. This is going to sound daft but how do I tell if it is condensation. If the tiles are porous then presumably they would hold the rain water for days and the water would gradually seep through.

 

[SurreyRoofingEstimator]

In the past we've had excperiences where there has been so much condensation that it was like a rain shower in the loft space so yes it really could casuse that much damp.

A house really does create a lot of moisture especially in the winter as generally windows and doors are kept shut and the heating is on full blast and what with hot showers and baths etc, that's a lot of steam and it only goes one way. Up.

 

[^woody^]

If the tiles are porous then presumably they would hold the rain water for days and the water would gradually seep through.

No, felt is impermeable, water does not seep through - otherwise why would it be used in the first place?

Water gets in via a hole - in which case is runs down in one place from a single point.

If everywhere is wet, then its not problem with the tiles or felt its from the air in the loft

 

[JohnE]

Thanks again for the help. I will look into the ventilation problem. However in my semi I only have one side of it that has guttering. There is the gap between the loft insulation and the soffits/guttering to allow air in but of course there is no through draft. In other words the front and back of the house has no guttering so no air vents. Would the answer be to have an air brick in both the front and back loft walls to obtain the proper ventilation/through draft?

 

[SurreyRoofingEstimator]

Ah, you have a gable front to back kinda roof, yes airbricks in the gable wall ends should help

 

[JohnE]

OK thanks.

I noticed in the posting about condensation "Woody" advises;

"increase the ceiling insulation and then go along and put your hand through the joint where the felt is lapped to open them up - a small bit of timber can be put in to keep them open in various places. This will do the same job as vents, only better".

My felt is the black plastic kind so I think I will give this a go before going for the air vents option. I was up in the loft last night and noticed that their is very little gap between the insulation and the eaves. I will also try and clear that.

 

[Shuflie]

Do you have an expansion tank for your heating system in the loft? I noticed my loft was very damp and had water dripping through after heavy rainfall in the winter. Like you I thought there was a problem with the roof until I looked in one evening and saw steam coming out of the expansion pipe. I called in a plumber who switched me over to a closed heating system and the damp problem cleared up and has been fine ever since.

 

[Alastairreid]

good point shuflie !

make sure any water tanks are well covered john.

 

[JohnE]

Ah thanks alastair/shuflie. Yes there is an expansion tank which is not particularly well covered. In fact the cover doesn't fit properly. I think the condensation could well be a combination of lack of ventilation and the hot expansion tank.

 

[Alastairreid]

i was working in an old house a few years back, the bedroom gable-end wall and ceiling was saturated in what we first thought was penetrating damp from the porous pebbledashed gable.
installed wall vents and cleaned off dirty wall ties, recasted gable.......

still dampness persisted. .
loft was dry with plenty of ventilation....some serious head scratching later we discovered a false wall in the attic against the gable end wall , behind which sat a header and expansion tank (uncovered to boot).
lol behind the partition was dripping with moisture.

the things people do. .