# Old bitumen flat pitch roof on house



## nubiwan (Sep 14, 2014)

Good day all. Searched the forum for a similar situation to my own, but no luck.

I have a 90+ year old house that has a low pitch roof on it. Probably plank over the trusses, but not confirmed. Roof currently has the rolled bitumen style roofing on it, and there are a few areas where roofing tar has been used to spot repair it. The roof is also not fully adhered to the surface as there appear to be air pockets here and there. Surface is not that smooth because of these pockets, on recollection, but I'd have to check this again to confirm how much movement there is. I am guessing 15-20 year old roof surface. No leaks inside at present, but evidence of some in the past. I am renovating the entire house. There are also 4 chimneys in the house? Pretty sure they have lead/metal flashing and tar.

Other than the chimneys, this roof is a simply low pitched peak and approximately 1200 square feet. Too low to shingle. I can attach roof pictures if required. Have attached pic of the house to illustrate pitch.

I want to resurface the roof, and would like to consider EPDM. 

Questions

1) Do I strip the roof or can I board over it, and adhere to the board?
2) If boarding is required then what kind of board is required for EPDM.
3) I have been told I can use solvent and simply lay the EPDM over top of the existing roof. Cutting out the uneven surface bits before laying the EPDM. Is this good information?
4) 45 mil or 60 mil EPDM for colder Canadian climate?

I have been quoted $12000 to put a 3 ply torched cover on this roof. Over top of the bitumen (to keep down costs - for who I thought). Conversely, I have been quoted $1300 for a 1500 square foot EPDM solution (Materials only). You can see why EPDM is so appealing.

There are no local EPDM installers, so I am going to have a DIY project on my hands. My crew normally works shingled roofs, so I am wonering how easy/hard EPDM is to work with.

Any suggestions would be welcomed.


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## 1985gt (Dec 21, 2010)

nubiwan said:


> Questions
> 
> 1) Do I strip the roof or can I board over it, and adhere to the board?
> 
> ...


EPDM is a fairly easy product but you do need some information, since you have little details it shouldn't be to bad. 

Another option is a self adhered modified roof. tear off, Nail the base, stick a 2nd layer of base, then stick the top cap sheet. Again watch the details around any penetrations.


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## nubiwan (Sep 14, 2014)

Thanks for that response 1985GT. Can I simply board over existing roof?


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## 1985gt (Dec 21, 2010)

You could. We haven't done a layover in a long time, to many issues to be concerned with, one being trapped moisture.


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## Grumpy (Oct 29, 2008)

If you are in for a quick flip, you may board over the existing roof. Maybe. Code might not allow it. If there is trapped moisture in the assembly, it's not advised. If the existing roof is uneven, the new roof will be uneven, though the cover board would remove some of the unevenness. 

I think there are alot of variables that we can't answer. Anything CAN be done, the real question is: Should it be done?


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