The same thing I did on the last one.....and every major renovation I've ever flipped. UNDER ESTIMATE THE REPAIRS AND THE TIME IN WHICH IT CAN GET DONE. I will however tell you, I don't really think that it's something I did "wrong". This dilemma is actually something that will keep you in check.
Okay, before you think I'm really bad at estimating know this. I have been involved in construction for 25 years. Real Estate for almost 20 years and I have NEVER had a project come in under budget or faster than expected. None of that matters. I guarantee it will happen on your first deal too. So I tell you this because you will think you failed or in some way missed something. It just happens. Expect it. accept it, and here is the key.........manage it. Here is what I mean.
For the purpose of this conversation I am going to assume the project needs some serious rehab. If it only needs a coat of paint, you can't hardly screw that up. I have wholesaled properties that needed little to no work and those obviously went fine. I am talking about at least $25k in renovation work. Here is an example:
If you purchase a house for $75k and estimate the repairs at $25k with an expected completion date of 4 weeks (I know those flipping shows say it only took them 4 days....I call BS). You will probably come in at $30K in repairs and 5 weeks to completion. That's about 20% OVER what you thought. Now these figures do vary. I have had some deals only go over by 5% all the way to 30%!!! (major miss on something unforeseen). But they ALL go over. Again expect it, accept it and manage it.
Things just can't always be accounted for in this business. There are too many moving parts, things that will surprise you, problems you just didn't see coming, things hidden beneath the surface, contractor delays, weather, etc, etc, etc.
Now most people may look at this and say....Well why not just add 20% to the budget if you know it's going to happen anyway? This way you will come in at cost. DUH! It doesn't work that way. I do actually add an overage figure to all my budgets and I STILL go over.
Here is the catch. When you estimate these projects, you can't be too generous with your budget. You have to keep it realistic yet ALMOST unattainable. Here's why....It gives you something to shoot for, a goal, a target.
Using the above example, let's say you decide to play it safe and just set your budget at $40k instead of $25K. How much do you think you will come in at? You guessed it! $40K. It's a false figure. You will assume you are safe and have plenty to work with. Even if you beat that by $5K you are still at $35K. Don't get all excited thinking you came in under budget on your first flip. You lost money. Go back to the original example. Set your budget at a slightly unattainable $25K. It's going to be tight and you know it. It keeps you honest, keeps you looking for discounts, working your contractors for breaks and forcing you to save, save, save EVERY place you can. You KNOW you have to stay on top of this or you will blow WAY past it. And when you do go over....by the 20%... now putting your repairs at $30K, you are at least $5-10K UNDER what an over-inflated, super safe, false budget does for you.
So coming full circle. It's not really what went "wrong" just something that WILL happen that I thought you should know. Just my two cents. I have done many flips. I still learn something on EVERY deal and I definitely don't have all the answers. That's what keeps this business exciting! I wish you the best of luck!