Get shipping amount from credit memo?

[The Tankgirl]

I've created a custom pdf invoice extension, and this works great with invoices. It's based on Firegento pdf. 
Now I want to edit the creditmemo pdf's and I'm trying to find out how to get the Creditmemo ShippingAmount

With normal invoices this is : $order-> getShippingAmount();

How can I do this with creditmemos?

I've tried to do this:

$creditmemoId = $this->getRequest()->getParam('creditmemo_id');
$creditmemo = Mage::getModel('sales/order_creditmemo')
                ->load($creditmemoId);
$shippingcosts = $creditmemo ->getShippingAmount();

But this gives me an error.. Can someone point me in the right direction?

Thanks in advance

[The Tankgirl · Accepted solution]

Ah got it, it's quite easy:

$order->getBaseShippingRefunded();