dmnf

有介紹, OB Roofing, 我13年前 揾過佢地, 兩年前也揾過佢地換而家住緊間屋, 信得過,
not sure if they do cedar.  Ask them to come and give you suggestions.  Their backlog is 1-2 months.  That means you have to wait for 1-2 months.  Winter time is 3-4 months because of rain.  Usually, good Roofers has long backlog.  Sears or other big names they have short wait time but they charge a lot.  For those whose roof is leaking, they don't have any choice.  Sounds like you have time to wait and shop around, give them a call.  Quote is free.

Aluminum roof lasts very long, people say 40-50 years.  But it is the most expensive one and mostly use in commercial buildings.  Some residential houses use it but not very common.  It is a big job and you may need to reinforce the roof before doing that.  I will say if you don't know much about it, do not consider.

dmnf

In addition, Aluminum roof is very noise when rain.  Not a good idea for Vancouver

dmnf

Usually the price different is due to insurance and warranty.  Big names like Sears has very  good guarantee.  In case there is problem, small contractors just walk away from it and you can only suit them in small claim court.  Big names since they have to cover themselves, they have to mark up a lot in order to do that.  Also, workmanship makes some different.  Most owners won't be able to inspect the job so I will say don't go for cheap ones.  

You should get at least 3 quotes and compare their estimates.  I only know Shingle for a normal size house is $5K-7K.  Cedar is much more expensive.  

Also, I was told cedar roof can be chemically treated before it reaches its end of life so that it can last 5-8 more years.  If you haven't done it, check it out.

dmnf

Roof 同 ceiling 之間有attic and thick insulation.  保暖隔熱, 屋頂物料對室內温度應該冇太大関係

重有換屋頂提議, since it is a big investment, especially cedar or Al., you can hold back the roofer 50% after they finish the job and then hire a house inspector to QA the job.  The inspection fee for just roof inspection should be $100-200.  Peace of mind.  However, don't expect an inspector can check everything.  All of these should be stated in the contract.

Therefore, if I had to do cedar roof, I would find a reputable one.  Or switch to common material like shingle.