Words of advice for future fume hood builders:
Try to stick to all plastic construction materials and especially avoid wood.
Reason: Wood absorbs acids, nitric or hydrochloric, and eventually becomes extremely flammable. We had a very large fire because the wood base on 2 fume hoods caught fire just from a hot plate being close. Just the heat from the hot plates caused the wood to catch fire.
Further, a fire extinguisher was used to suppress the fire, and the user thought he had completely extinguished it so he called the fire department to cancel the fire alarm. In the few minutes it took him to do that, the wood had re-ignited and most everything in the room was fully engulfed in flames. Well over 100K in damage and we had a 10K deductible on our insurance coverage. It was an expensive way to find out.
Ever since, we have made everything out of plastic and 15 years later it is still intact. PVC, Polypropylene, FRP, all plastics work well.